* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE [not found] ` <20200405045709-mutt-send-email-mst@kernel.org> @ 2020-04-05 16:43 ` Michael S. Tsirkin 2020-04-06 10:00 ` Ard Biesheuvel 0 siblings, 1 reply; 7+ messages in thread From: Michael S. Tsirkin @ 2020-04-05 16:43 UTC (permalink / raw) To: kbuild test robot Cc: kbuild-all, Jason Wang, daniel.santos, Russell King, Ard Biesheuvel, linux-arm-kernel Hello! I would appreciate ARM maintainers take on the following (sorry if I forgot someone, pls feel free to add people to CC): On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > > config: arm-randconfig-a001-20200405 (attached as .config) > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > > reproduce: > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > chmod +x ~/bin/make.cross > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > > # save the attached .config to linux build tree > > GCC_VERSION=9.3.0 make.cross ARCH=arm > > > > If you fix the issue, kindly add following tag as appropriate > > Reported-by: kbuild test robot <lkp@intel.com> > > > > All error/warnings (new ones prefixed by >>): > > > > In file included from include/linux/kernel.h:11, > > from include/linux/list.h:9, > > from include/linux/preempt.h:11, > > from include/linux/spinlock.h:51, > > from include/linux/seqlock.h:36, > > from include/linux/time.h:6, > > from include/linux/stat.h:19, > > from include/linux/fcntl.h:5, > > from include/linux/eventfd.h:12, > > from drivers/vhost/vhost.c:13: > > In function 'vhost_vring_set_addr', > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > | ^ > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > > 331 | prefix ## suffix(); \ > > | ^~~~~~ > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > | ^~~~~~~~~~~~~~~~~~~ > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > | ^~~~~~~~~~~~~~~~~~ > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > | ^~~~~~~~~~~~~~~~ > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > > | ^~~~~~~~~~~~ > > This compiler seems to be broken. We have: > #define VRING_AVAIL_ALIGN_SIZE 2 > and > > struct vring_avail __user *avail; > > and > struct vring_avail { > __virtio16 flags; > __virtio16 idx; > __virtio16 ring[]; > }; > > A compiler that decides to require alignment of > 2 bytes on > a struct of packed u16's is likely broken in a bunch of other > ways that just happen not to trigger a BUILD_BUG. > > > The commit referenced just enables build on more platforms ... OK after some research, it seems that the issue triggers with latest gcc too. To trigger it, supply -mabi=apcs-gnu on command line. Dropping -mabi=apcs-gnu fixes the build. I am still researching this flag. > > vim +/__compiletime_assert_1533 +350 include/linux/compiler.h > > > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 336 > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 337 #define _compiletime_assert(condition, msg, prefix, suffix) \ > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 338 __compiletime_assert(condition, msg, prefix, suffix) > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 339 > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 340 /** > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 341 * compiletime_assert - break build and emit msg if condition is false > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 342 * @condition: a compile-time constant condition to check > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 343 * @msg: a message to emit if condition is false > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 344 * > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 345 * In tradition of POSIX assert, this macro will break the build if the > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 346 * supplied condition is *false*, emitting the supplied error message if the > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 347 * compiler has support to do so. > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 348 */ > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 349 #define compiletime_assert(condition, msg) \ > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 @350 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > 9a8ab1c39970a4 Daniel Santos 2013-02-21 351 > > > > :::::: The code at line 350 was first introduced by commit > > :::::: 9a8ab1c39970a4938a72d94e6fd13be88a797590 bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG > > > > :::::: TO: Daniel Santos <daniel.santos@pobox.com> > > :::::: CC: Linus Torvalds <torvalds@linux-foundation.org> > > > > --- > > 0-DAY CI Kernel Test Service, Intel Corporation > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-05 16:43 ` [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE Michael S. Tsirkin @ 2020-04-06 10:00 ` Ard Biesheuvel 2020-04-06 10:38 ` Michael S. Tsirkin 0 siblings, 1 reply; 7+ messages in thread From: Ard Biesheuvel @ 2020-04-06 10:00 UTC (permalink / raw) To: Michael S. Tsirkin, richard.henderson, christophe.lyon, richard.earnshaw Cc: kbuild-all, kbuild test robot, Jason Wang, daniel.santos, Russell King, Linux ARM (adding some ARM GCC folks) On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: > > Hello! > I would appreciate ARM maintainers take on the following > (sorry if I forgot someone, pls feel free to add people to CC): > > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > > > config: arm-randconfig-a001-20200405 (attached as .config) > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > > > reproduce: > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > chmod +x ~/bin/make.cross > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > > > # save the attached .config to linux build tree > > > GCC_VERSION=9.3.0 make.cross ARCH=arm > > > > > > If you fix the issue, kindly add following tag as appropriate > > > Reported-by: kbuild test robot <lkp@intel.com> > > > > > > All error/warnings (new ones prefixed by >>): > > > > > > In file included from include/linux/kernel.h:11, > > > from include/linux/list.h:9, > > > from include/linux/preempt.h:11, > > > from include/linux/spinlock.h:51, > > > from include/linux/seqlock.h:36, > > > from include/linux/time.h:6, > > > from include/linux/stat.h:19, > > > from include/linux/fcntl.h:5, > > > from include/linux/eventfd.h:12, > > > from drivers/vhost/vhost.c:13: > > > In function 'vhost_vring_set_addr', > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > | ^ > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > > > 331 | prefix ## suffix(); \ > > > | ^~~~~~ > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > | ^~~~~~~~~~~~~~~~~~~ > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > > | ^~~~~~~~~~~~~~~~~~ > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > > | ^~~~~~~~~~~~~~~~ > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > > > | ^~~~~~~~~~~~ > > > > This compiler seems to be broken. We have: > > #define VRING_AVAIL_ALIGN_SIZE 2 > > and > > > > struct vring_avail __user *avail; > > > > and > > struct vring_avail { > > __virtio16 flags; > > __virtio16 idx; > > __virtio16 ring[]; > > }; > > > > A compiler that decides to require alignment of > 2 bytes on > > a struct of packed u16's is likely broken in a bunch of other > > ways that just happen not to trigger a BUILD_BUG. > > > > > > The commit referenced just enables build on more platforms ... > > OK after some research, it seems that the issue triggers with > latest gcc too. > To trigger it, supply -mabi=apcs-gnu on command line. > > Dropping -mabi=apcs-gnu fixes the build. > > I am still researching this flag. > Is there a difference between __alignof__ *vq->avail and __alignof__(struct vring_avail) ? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-06 10:00 ` Ard Biesheuvel @ 2020-04-06 10:38 ` Michael S. Tsirkin 2020-04-06 10:49 ` Ard Biesheuvel 0 siblings, 1 reply; 7+ messages in thread From: Michael S. Tsirkin @ 2020-04-06 10:38 UTC (permalink / raw) To: Ard Biesheuvel Cc: richard.earnshaw, kbuild-all, kbuild test robot, christophe.lyon, Jason Wang, richard.henderson, daniel.santos, Russell King, Linux ARM On Mon, Apr 06, 2020 at 12:00:36PM +0200, Ard Biesheuvel wrote: > (adding some ARM GCC folks) > > > On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: > > > > Hello! > > I would appreciate ARM maintainers take on the following > > (sorry if I forgot someone, pls feel free to add people to CC): > > > > > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > > > > config: arm-randconfig-a001-20200405 (attached as .config) > > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > > > > reproduce: > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > > chmod +x ~/bin/make.cross > > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > > > > # save the attached .config to linux build tree > > > > GCC_VERSION=9.3.0 make.cross ARCH=arm > > > > > > > > If you fix the issue, kindly add following tag as appropriate > > > > Reported-by: kbuild test robot <lkp@intel.com> > > > > > > > > All error/warnings (new ones prefixed by >>): > > > > > > > > In file included from include/linux/kernel.h:11, > > > > from include/linux/list.h:9, > > > > from include/linux/preempt.h:11, > > > > from include/linux/spinlock.h:51, > > > > from include/linux/seqlock.h:36, > > > > from include/linux/time.h:6, > > > > from include/linux/stat.h:19, > > > > from include/linux/fcntl.h:5, > > > > from include/linux/eventfd.h:12, > > > > from drivers/vhost/vhost.c:13: > > > > In function 'vhost_vring_set_addr', > > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > | ^ > > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > > > > 331 | prefix ## suffix(); \ > > > > | ^~~~~~ > > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > | ^~~~~~~~~~~~~~~~~~~ > > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > > > | ^~~~~~~~~~~~~~~~~~ > > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > > > | ^~~~~~~~~~~~~~~~ > > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > > > > | ^~~~~~~~~~~~ > > > > > > This compiler seems to be broken. We have: > > > #define VRING_AVAIL_ALIGN_SIZE 2 > > > and > > > > > > struct vring_avail __user *avail; > > > > > > and > > > struct vring_avail { > > > __virtio16 flags; > > > __virtio16 idx; > > > __virtio16 ring[]; > > > }; > > > > > > A compiler that decides to require alignment of > 2 bytes on > > > a struct of packed u16's is likely broken in a bunch of other > > > ways that just happen not to trigger a BUILD_BUG. > > > > > > > > > The commit referenced just enables build on more platforms ... > > > > OK after some research, it seems that the issue triggers with > > latest gcc too. > > To trigger it, supply -mabi=apcs-gnu on command line. > > > > Dropping -mabi=apcs-gnu fixes the build. > > > > I am still researching this flag. > > > > Is there a difference between __alignof__ *vq->avail and > __alignof__(struct vring_avail) ? Yes, the same. I found this: https://stackoverflow.com/questions/43786747/struct-layout-in-apcs-gnu-abi Not sure how to interpret it ... -- MST _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-06 10:38 ` Michael S. Tsirkin @ 2020-04-06 10:49 ` Ard Biesheuvel 2020-04-06 10:56 ` Richard Earnshaw 2020-04-06 11:36 ` Michael S. Tsirkin 0 siblings, 2 replies; 7+ messages in thread From: Ard Biesheuvel @ 2020-04-06 10:49 UTC (permalink / raw) To: Michael S. Tsirkin Cc: richard.earnshaw, kbuild-all, kbuild test robot, christophe.lyon, Jason Wang, richard.henderson, daniel.santos, Russell King, Linux ARM On Mon, 6 Apr 2020 at 12:38, Michael S. Tsirkin <mst@redhat.com> wrote: > > On Mon, Apr 06, 2020 at 12:00:36PM +0200, Ard Biesheuvel wrote: > > (adding some ARM GCC folks) > > > > > > On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: > > > > > > Hello! > > > I would appreciate ARM maintainers take on the following > > > (sorry if I forgot someone, pls feel free to add people to CC): > > > > > > > > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > > > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > > > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > > > > > config: arm-randconfig-a001-20200405 (attached as .config) > > > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > > > > > reproduce: > > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > > > chmod +x ~/bin/make.cross > > > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > > > > > # save the attached .config to linux build tree > > > > > GCC_VERSION=9.3.0 make.cross ARCH=arm > > > > > > > > > > If you fix the issue, kindly add following tag as appropriate > > > > > Reported-by: kbuild test robot <lkp@intel.com> > > > > > > > > > > All error/warnings (new ones prefixed by >>): > > > > > > > > > > In file included from include/linux/kernel.h:11, > > > > > from include/linux/list.h:9, > > > > > from include/linux/preempt.h:11, > > > > > from include/linux/spinlock.h:51, > > > > > from include/linux/seqlock.h:36, > > > > > from include/linux/time.h:6, > > > > > from include/linux/stat.h:19, > > > > > from include/linux/fcntl.h:5, > > > > > from include/linux/eventfd.h:12, > > > > > from drivers/vhost/vhost.c:13: > > > > > In function 'vhost_vring_set_addr', > > > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > > > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > > > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > > | ^ > > > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > > > > > 331 | prefix ## suffix(); \ > > > > > | ^~~~~~ > > > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > > | ^~~~~~~~~~~~~~~~~~~ > > > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > > > > | ^~~~~~~~~~~~~~~~~~ > > > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > > > > | ^~~~~~~~~~~~~~~~ > > > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > > > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > > > > > | ^~~~~~~~~~~~ > > > > > > > > This compiler seems to be broken. We have: > > > > #define VRING_AVAIL_ALIGN_SIZE 2 > > > > and > > > > > > > > struct vring_avail __user *avail; > > > > > > > > and > > > > struct vring_avail { > > > > __virtio16 flags; > > > > __virtio16 idx; > > > > __virtio16 ring[]; > > > > }; > > > > > > > > A compiler that decides to require alignment of > 2 bytes on > > > > a struct of packed u16's is likely broken in a bunch of other > > > > ways that just happen not to trigger a BUILD_BUG. > > > > > > > > > > > > The commit referenced just enables build on more platforms ... > > > > > > OK after some research, it seems that the issue triggers with > > > latest gcc too. > > > To trigger it, supply -mabi=apcs-gnu on command line. > > > > > > Dropping -mabi=apcs-gnu fixes the build. > > > > > > I am still researching this flag. > > > > > > > Is there a difference between __alignof__ *vq->avail and > > __alignof__(struct vring_avail) ? > > Yes, the same. > I found this: > https://stackoverflow.com/questions/43786747/struct-layout-in-apcs-gnu-abi > > Not sure how to interpret it ... Ah right, I missed that apcs-gnu is the ancient OABI that is been deprecated for a long time. Given that virtio support on such ancient systems is not needed in the first place, let's just add something along the lines of depends on !ARM || AEABI to the virtio Kconfig declaration, and add a comment that it has to do with struct member alignment. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-06 10:49 ` Ard Biesheuvel @ 2020-04-06 10:56 ` Richard Earnshaw 2020-04-06 11:43 ` Michael S. Tsirkin 2020-04-06 11:36 ` Michael S. Tsirkin 1 sibling, 1 reply; 7+ messages in thread From: Richard Earnshaw @ 2020-04-06 10:56 UTC (permalink / raw) To: Ard Biesheuvel, Michael S. Tsirkin Cc: kbuild-all@lists.01.org, kbuild test robot, daniel.santos@pobox.com, Jason Wang, richard.henderson@linaro.org, christophe.lyon@st.com, Russell King, Linux ARM On 06/04/2020 11:49, Ard Biesheuvel wrote: > On Mon, 6 Apr 2020 at 12:38, Michael S. Tsirkin <mst@redhat.com> wrote: >> >> On Mon, Apr 06, 2020 at 12:00:36PM +0200, Ard Biesheuvel wrote: >> > (adding some ARM GCC folks) >> > >> > >> > On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: >> > > >> > > Hello! >> > > I would appreciate ARM maintainers take on the following >> > > (sorry if I forgot someone, pls feel free to add people to CC): >> > > >> > > >> > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: >> > > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: >> > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master >> > > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 >> > > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig >> > > > > config: arm-randconfig-a001-20200405 (attached as .config) >> > > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 >> > > > > reproduce: >> > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross > -O ~/bin/make.cross >> > > > > chmod +x ~/bin/make.cross >> > > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 >> > > > > # save the attached .config to linux build tree >> > > > > GCC_VERSION=9.3.0 make.cross ARCH=arm >> > > > > >> > > > > If you fix the issue, kindly add following tag as appropriate >> > > > > Reported-by: kbuild test robot <lkp@intel.com> >> > > > > >> > > > > All error/warnings (new ones prefixed by >>): >> > > > > >> > > > > In file included from include/linux/kernel.h:11, >> > > > > from include/linux/list.h:9, >> > > > > from include/linux/preempt.h:11, >> > > > > from include/linux/spinlock.h:51, >> > > > > from include/linux/seqlock.h:36, >> > > > > from include/linux/time.h:6, >> > > > > from include/linux/stat.h:19, >> > > > > from include/linux/fcntl.h:5, >> > > > > from include/linux/eventfd.h:12, >> > > > > from drivers/vhost/vhost.c:13: >> > > > > In function 'vhost_vring_set_addr', >> > > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, >> > > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: >> > > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE >> > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) >> > > > > | ^ >> > > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' >> > > > > 331 | prefix ## suffix(); \ >> > > > > | ^~~~~~ >> > > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' >> > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) >> > > > > | ^~~~~~~~~~~~~~~~~~~ >> > > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' >> > > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) >> > > > > | ^~~~~~~~~~~~~~~~~~ >> > > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' >> > > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) >> > > > > | ^~~~~~~~~~~~~~~~ >> > > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' >> > > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); >> > > > > | ^~~~~~~~~~~~ >> > > > >> > > > This compiler seems to be broken. We have: >> > > > #define VRING_AVAIL_ALIGN_SIZE 2 >> > > > and >> > > > >> > > > struct vring_avail __user *avail; >> > > > >> > > > and >> > > > struct vring_avail { >> > > > __virtio16 flags; >> > > > __virtio16 idx; >> > > > __virtio16 ring[]; >> > > > }; >> > > > >> > > > A compiler that decides to require alignment of > 2 bytes on >> > > > a struct of packed u16's is likely broken in a bunch of other >> > > > ways that just happen not to trigger a BUILD_BUG. >> > > > >> > > > >> > > > The commit referenced just enables build on more platforms ... >> > > >> > > OK after some research, it seems that the issue triggers with >> > > latest gcc too. >> > > To trigger it, supply -mabi=apcs-gnu on command line. >> > > >> > > Dropping -mabi=apcs-gnu fixes the build. >> > > >> > > I am still researching this flag. >> > > >> > >> > Is there a difference between __alignof__ *vq->avail and >> > __alignof__(struct vring_avail) ? >> >> Yes, the same. >> I found this: >> https://stackoverflow.com/questions/43786747/struct-layout-in-apcs-gnu-abi >> >> Not sure how to interpret it ... > > Ah right, I missed that apcs-gnu is the ancient OABI that is been > deprecated for a long time. > > Given that virtio support on such ancient systems is not needed in the > first place, let's just add something along the lines of > > depends on !ARM || AEABI > > to the virtio Kconfig declaration, and add a comment that it has to do > with struct member alignment. apcs-gnu is deprecated. The plan is to remove it entirely in the not too distant future now that all platforms that previously used it have migrated to the aapcs. R. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-06 10:56 ` Richard Earnshaw @ 2020-04-06 11:43 ` Michael S. Tsirkin 0 siblings, 0 replies; 7+ messages in thread From: Michael S. Tsirkin @ 2020-04-06 11:43 UTC (permalink / raw) To: Richard Earnshaw Cc: kbuild-all@lists.01.org, kbuild test robot, christophe.lyon@st.com, Jason Wang, richard.henderson@linaro.org, daniel.santos@pobox.com, Russell King, Ard Biesheuvel, Linux ARM On Mon, Apr 06, 2020 at 11:56:24AM +0100, Richard Earnshaw wrote: > On 06/04/2020 11:49, Ard Biesheuvel wrote: > > On Mon, 6 Apr 2020 at 12:38, Michael S. Tsirkin <mst@redhat.com> wrote: > >> > >> On Mon, Apr 06, 2020 at 12:00:36PM +0200, Ard Biesheuvel wrote: > >> > (adding some ARM GCC folks) > >> > > >> > > >> > On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: > >> > > > >> > > Hello! > >> > > I would appreciate ARM maintainers take on the following > >> > > (sorry if I forgot someone, pls feel free to add people to CC): > >> > > > >> > > > >> > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > >> > > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > >> > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > >> > > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > >> > > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > >> > > > > config: arm-randconfig-a001-20200405 (attached as .config) > >> > > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > >> > > > > reproduce: > >> > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross > > -O ~/bin/make.cross > >> > > > > chmod +x ~/bin/make.cross > >> > > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > >> > > > > # save the attached .config to linux build tree > >> > > > > GCC_VERSION=9.3.0 make.cross ARCH=arm > >> > > > > > >> > > > > If you fix the issue, kindly add following tag as appropriate > >> > > > > Reported-by: kbuild test robot <lkp@intel.com> > >> > > > > > >> > > > > All error/warnings (new ones prefixed by >>): > >> > > > > > >> > > > > In file included from include/linux/kernel.h:11, > >> > > > > from include/linux/list.h:9, > >> > > > > from include/linux/preempt.h:11, > >> > > > > from include/linux/spinlock.h:51, > >> > > > > from include/linux/seqlock.h:36, > >> > > > > from include/linux/time.h:6, > >> > > > > from include/linux/stat.h:19, > >> > > > > from include/linux/fcntl.h:5, > >> > > > > from include/linux/eventfd.h:12, > >> > > > > from drivers/vhost/vhost.c:13: > >> > > > > In function 'vhost_vring_set_addr', > >> > > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > >> > > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > >> > > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > >> > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > >> > > > > | ^ > >> > > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > >> > > > > 331 | prefix ## suffix(); \ > >> > > > > | ^~~~~~ > >> > > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > >> > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > >> > > > > | ^~~~~~~~~~~~~~~~~~~ > >> > > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > >> > > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > >> > > > > | ^~~~~~~~~~~~~~~~~~ > >> > > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > >> > > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > >> > > > > | ^~~~~~~~~~~~~~~~ > >> > > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > >> > > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > >> > > > > | ^~~~~~~~~~~~ > >> > > > > >> > > > This compiler seems to be broken. We have: > >> > > > #define VRING_AVAIL_ALIGN_SIZE 2 > >> > > > and > >> > > > > >> > > > struct vring_avail __user *avail; > >> > > > > >> > > > and > >> > > > struct vring_avail { > >> > > > __virtio16 flags; > >> > > > __virtio16 idx; > >> > > > __virtio16 ring[]; > >> > > > }; > >> > > > > >> > > > A compiler that decides to require alignment of > 2 bytes on > >> > > > a struct of packed u16's is likely broken in a bunch of other > >> > > > ways that just happen not to trigger a BUILD_BUG. > >> > > > > >> > > > > >> > > > The commit referenced just enables build on more platforms ... > >> > > > >> > > OK after some research, it seems that the issue triggers with > >> > > latest gcc too. > >> > > To trigger it, supply -mabi=apcs-gnu on command line. > >> > > > >> > > Dropping -mabi=apcs-gnu fixes the build. > >> > > > >> > > I am still researching this flag. > >> > > > >> > > >> > Is there a difference between __alignof__ *vq->avail and > >> > __alignof__(struct vring_avail) ? > >> > >> Yes, the same. > >> I found this: > >> https://stackoverflow.com/questions/43786747/struct-layout-in-apcs-gnu-abi > >> > >> Not sure how to interpret it ... > > > > Ah right, I missed that apcs-gnu is the ancient OABI that is been > > deprecated for a long time. > > > > Given that virtio support on such ancient systems is not needed in the > > first place, let's just add something along the lines of > > > > depends on !ARM || AEABI > > > > to the virtio Kconfig declaration, and add a comment that it has to do > > with struct member alignment. > > apcs-gnu is deprecated. The plan is to remove it entirely in the not > too distant future now that all platforms that previously used it have > migrated to the aapcs. Problem is that the default ARM build still uses that. That includes the kbuild infrastructure. > R. > IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE 2020-04-06 10:49 ` Ard Biesheuvel 2020-04-06 10:56 ` Richard Earnshaw @ 2020-04-06 11:36 ` Michael S. Tsirkin 1 sibling, 0 replies; 7+ messages in thread From: Michael S. Tsirkin @ 2020-04-06 11:36 UTC (permalink / raw) To: Ard Biesheuvel Cc: richard.earnshaw, kbuild-all, kbuild test robot, christophe.lyon, Jason Wang, richard.henderson, daniel.santos, Russell King, Linux ARM On Mon, Apr 06, 2020 at 12:49:55PM +0200, Ard Biesheuvel wrote: > On Mon, 6 Apr 2020 at 12:38, Michael S. Tsirkin <mst@redhat.com> wrote: > > > > On Mon, Apr 06, 2020 at 12:00:36PM +0200, Ard Biesheuvel wrote: > > > (adding some ARM GCC folks) > > > > > > > > > On Sun, 5 Apr 2020 at 18:44, Michael S. Tsirkin <mst@redhat.com> wrote: > > > > > > > > Hello! > > > > I would appreciate ARM maintainers take on the following > > > > (sorry if I forgot someone, pls feel free to add people to CC): > > > > > > > > > > > > On Sun, Apr 05, 2020 at 05:01:01AM -0400, Michael S. Tsirkin wrote: > > > > > On Sun, Apr 05, 2020 at 07:57:24AM +0800, kbuild test robot wrote: > > > > > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > > > > > > head: dff79597431045a775f2e5d4d9de31bfa0d32a34 > > > > > > commit: 20c384f1ea1a0bc7320bc445c72dd02d2970d594 [12804/13809] vhost: refine vhost and vringh kconfig > > > > > > config: arm-randconfig-a001-20200405 (attached as .config) > > > > > > compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 > > > > > > reproduce: > > > > > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > > > > > chmod +x ~/bin/make.cross > > > > > > git checkout 20c384f1ea1a0bc7320bc445c72dd02d2970d594 > > > > > > # save the attached .config to linux build tree > > > > > > GCC_VERSION=9.3.0 make.cross ARCH=arm > > > > > > > > > > > > If you fix the issue, kindly add following tag as appropriate > > > > > > Reported-by: kbuild test robot <lkp@intel.com> > > > > > > > > > > > > All error/warnings (new ones prefixed by >>): > > > > > > > > > > > > In file included from include/linux/kernel.h:11, > > > > > > from include/linux/list.h:9, > > > > > > from include/linux/preempt.h:11, > > > > > > from include/linux/spinlock.h:51, > > > > > > from include/linux/seqlock.h:36, > > > > > > from include/linux/time.h:6, > > > > > > from include/linux/stat.h:19, > > > > > > from include/linux/fcntl.h:5, > > > > > > from include/linux/eventfd.h:12, > > > > > > from drivers/vhost/vhost.c:13: > > > > > > In function 'vhost_vring_set_addr', > > > > > > inlined from 'vhost_vring_set_num_addr' at drivers/vhost/vhost.c:1581:7, > > > > > > inlined from 'vhost_vring_ioctl' at drivers/vhost/vhost.c:1614:10: > > > > > > >> include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE > > > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > > > | ^ > > > > > > include/linux/compiler.h:331:4: note: in definition of macro '__compiletime_assert' > > > > > > 331 | prefix ## suffix(); \ > > > > > > | ^~~~~~ > > > > > > include/linux/compiler.h:350:2: note: in expansion of macro '_compiletime_assert' > > > > > > 350 | _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > > > > > | ^~~~~~~~~~~~~~~~~~~ > > > > > > include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' > > > > > > 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > > > > > | ^~~~~~~~~~~~~~~~~~ > > > > > > include/linux/build_bug.h:50:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' > > > > > > 50 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > > > > > | ^~~~~~~~~~~~~~~~ > > > > > > >> drivers/vhost/vhost.c:1533:2: note: in expansion of macro 'BUILD_BUG_ON' > > > > > > 1533 | BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE); > > > > > > | ^~~~~~~~~~~~ > > > > > > > > > > This compiler seems to be broken. We have: > > > > > #define VRING_AVAIL_ALIGN_SIZE 2 > > > > > and > > > > > > > > > > struct vring_avail __user *avail; > > > > > > > > > > and > > > > > struct vring_avail { > > > > > __virtio16 flags; > > > > > __virtio16 idx; > > > > > __virtio16 ring[]; > > > > > }; > > > > > > > > > > A compiler that decides to require alignment of > 2 bytes on > > > > > a struct of packed u16's is likely broken in a bunch of other > > > > > ways that just happen not to trigger a BUILD_BUG. > > > > > > > > > > > > > > > The commit referenced just enables build on more platforms ... > > > > > > > > OK after some research, it seems that the issue triggers with > > > > latest gcc too. > > > > To trigger it, supply -mabi=apcs-gnu on command line. > > > > > > > > Dropping -mabi=apcs-gnu fixes the build. > > > > > > > > I am still researching this flag. > > > > > > > > > > Is there a difference between __alignof__ *vq->avail and > > > __alignof__(struct vring_avail) ? > > > > Yes, the same. > > I found this: > > https://stackoverflow.com/questions/43786747/struct-layout-in-apcs-gnu-abi > > > > Not sure how to interpret it ... > > Ah right, I missed that apcs-gnu is the ancient OABI that is been > deprecated for a long time. > > Given that virtio support on such ancient systems is not needed in the > first place, let's just add something along the lines of > > depends on !ARM || AEABI > > to the virtio Kconfig declaration, and add a comment that it has to do > with struct member alignment. The annoying thing is that the component which has this alignment requirement is actually vhost which is selected, so we can not add dependencies to it. -- MST _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-04-06 11:43 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
[not found] <202004050718.B9NaFC2U%lkp@intel.com>
[not found] ` <20200405045709-mutt-send-email-mst@kernel.org>
2020-04-05 16:43 ` [linux-next:master 12804/13809] include/linux/compiler.h:350:38: error: call to '__compiletime_assert_1533' declared with attribute error: BUILD_BUG_ON failed: __alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE Michael S. Tsirkin
2020-04-06 10:00 ` Ard Biesheuvel
2020-04-06 10:38 ` Michael S. Tsirkin
2020-04-06 10:49 ` Ard Biesheuvel
2020-04-06 10:56 ` Richard Earnshaw
2020-04-06 11:43 ` Michael S. Tsirkin
2020-04-06 11:36 ` Michael S. Tsirkin
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).