[patch 1/4] Configure out AIO support

[patch 1/4] Configure out AIO support

[Thomas Petazzoni]

[-- Attachment #1: configure-out-aio-support --]
[-- Type: text/plain, Size: 4841 bytes --]

This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:

   text	   data	    bss	    dec	    hex	filename
1115067	 119180	 217088	1451335	 162547	vmlinux
1108025	 119048	 217088	1444161	 160941	vmlinux.new
  -7042    -132       0   -7174   -1C06 +/-

This patch has been originally written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: bcrl@kvack.org
Cc: linux-aio@kvack.org
Cc: mpm@selenic.com
Cc: akpm@linux-foundation.org


---
 fs/Makefile         |    3 ++-
 include/linux/aio.h |    9 +++++++++
 init/Kconfig        |    8 ++++++++
 kernel/sys_ni.c     |    5 +++++
 kernel/sysctl.c     |    2 ++
 5 files changed, 26 insertions(+), 1 deletion(-)

Index: linuxdev/fs/Makefile
===================================================================
--- linuxdev.orig/fs/Makefile
+++ linuxdev/fs/Makefile
@@ -8,7 +8,7 @@
 obj-y :=	open.o read_write.o file_table.o super.o \
 		char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
 		ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
-		attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
+		attr.o bad_inode.o file.o filesystems.o namespace.o \
 		seq_file.o xattr.o libfs.o fs-writeback.o \
 		pnode.o drop_caches.o splice.o sync.o utimes.o \
 		stack.o
@@ -27,6 +27,7 @@
 obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
+obj-$(CONFIG_AIO)               += aio.o
 obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o
 
 nfsd-$(CONFIG_NFSD)		:= nfsctl.o
Index: linuxdev/include/linux/aio.h
===================================================================
--- linuxdev.orig/include/linux/aio.h
+++ linuxdev/include/linux/aio.h
@@ -204,12 +204,21 @@
 /* prototypes */
 extern unsigned aio_max_size;
 
+#ifdef CONFIG_AIO
 extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
 extern int aio_put_req(struct kiocb *iocb);
 extern void kick_iocb(struct kiocb *iocb);
 extern int aio_complete(struct kiocb *iocb, long res, long res2);
 struct mm_struct;
 extern void exit_aio(struct mm_struct *mm);
+#else
+static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
+static inline int aio_put_req(struct kiocb *iocb) { return 0; }
+static inline void kick_iocb(struct kiocb *iocb) { }
+static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
+struct mm_struct;
+static inline void exit_aio(struct mm_struct *mm) { }
+#endif /* CONFIG_AIO */
 
 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 
Index: linuxdev/init/Kconfig
===================================================================
--- linuxdev.orig/init/Kconfig
+++ linuxdev/init/Kconfig
@@ -724,6 +724,14 @@
 	  option replaces shmem and tmpfs with the much simpler ramfs code,
 	  which may be appropriate on small systems without swap.
 
+config AIO
+	bool "Enable AIO support" if EMBEDDED
+	default y
+	help
+	  This option enables POSIX asynchronous I/O which may by used
+          by some high performance threaded applications. Disabling
+          this option saves about 7k.
+
 config VM_EVENT_COUNTERS
 	default y
 	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
Index: linuxdev/kernel/sys_ni.c
===================================================================
--- linuxdev.orig/kernel/sys_ni.c
+++ linuxdev/kernel/sys_ni.c
@@ -125,6 +125,11 @@
 cond_syscall(sys_vm86);
 cond_syscall(compat_sys_ipc);
 cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_io_setup);
+cond_syscall(sys_io_destroy);
+cond_syscall(sys_io_submit);
+cond_syscall(sys_io_cancel);
+cond_syscall(sys_io_getevents);
 
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);
Index: linuxdev/kernel/sysctl.c
===================================================================
--- linuxdev.orig/kernel/sysctl.c
+++ linuxdev/kernel/sysctl.c
@@ -1290,6 +1290,7 @@
 		.extra1		= &zero,
 		.extra2		= &two,
 	},
+#ifdef CONFIG_AIO
 	{
 		.procname	= "aio-nr",
 		.data		= &aio_nr,
@@ -1304,6 +1305,7 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_doulongvec_minmax,
 	},
+#endif /* CONFIG_AIO */
 #ifdef CONFIG_INOTIFY_USER
 	{
 		.ctl_name	= FS_INOTIFY,

-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com

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Re: [patch 1/4] Configure out AIO support

[Matt Mackall]

On Tue, 2008-07-29 at 17:45 +0200, Thomas Petazzoni wrote:
> plain text document attachment (configure-out-aio-support)
> This patchs adds the CONFIG_AIO option which allows to remove support
> for asynchronous I/O operations, that are not necessarly used by
> applications, particularly on embedded devices. As this is a
> size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> save ~7 kilobytes of kernel code/data:
> 
>    text	   data	    bss	    dec	    hex	filename
> 1115067	 119180	 217088	1451335	 162547	vmlinux
> 1108025	 119048	 217088	1444161	 160941	vmlinux.new
>   -7042    -132       0   -7174   -1C06 +/-
> 
> This patch has been originally written by Matt Mackall
> <mpm@selenic.com>, and is part of the Linux Tiny project.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> Cc: bcrl@kvack.org
> Cc: linux-aio@kvack.org
> Cc: mpm@selenic.com
> Cc: akpm@linux-foundation.org

These all look good to me, naturally.

Signed-off-by: Matt Mackall <mpm@selenic.com>

-- 
Mathematics is the supreme nostalgia of our time.

Re: [patch 2/4] Configure out file locking features

[Matthew Wilcox]

On Tue, Jul 29, 2008 at 05:45:22PM +0200, Thomas Petazzoni wrote:
> This patch adds the CONFIG_FILE_LOCKING option which allows to remove
> support for advisory locks. With this patch enabled, the flock()
> system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
> and NFS support are disabled. These features are not necessarly needed
> on embedded systems. It allows to save ~11 Kb of kernel code and data:
> 
>    text	   data	    bss	    dec	    hex	filename
> 1125436	 118764	 212992	1457192	 163c28	vmlinux.old
> 1114299	 118564	 212992	1445855	 160fdf	vmlinux
>  -11137    -200       0  -11337   -2C49 +/-
> 
> This patch has originally been written by Matt Mackall
> <mpm@selenic.com>, and is part of the Linux Tiny project.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

In principle, I think this is a great idea.

>  config NFS_FS
>  	tristate "NFS client support"
> -	depends on INET
> +	depends on INET && FILE_LOCKING
>  	select LOCKD
>  	select SUNRPC
>  	select NFS_ACL_SUPPORT if NFS_V3_ACL

I think this part is a little lazy.  It should be possible to support
NFS without file locking.  I suspect that's really not in-scope for the
linux-tiny tree as currently envisaged with the focus on embedded
devices that probably don't use NFS anyway.  Do we want to care about
the situation of a machine with fixed workload, that doesn't need file
locking, but does use NFS?

-- 
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"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

Re: [patch 2/4] Configure out file locking features

[Matt Mackall]

On Tue, 2008-07-29 at 12:17 -0600, Matthew Wilcox wrote:
> On Tue, Jul 29, 2008 at 05:45:22PM +0200, Thomas Petazzoni wrote:
> > This patch adds the CONFIG_FILE_LOCKING option which allows to remove
> > support for advisory locks. With this patch enabled, the flock()
> > system call, the F_GETLK, F_SETLK and F_SETLKW operations of fcntl()
> > and NFS support are disabled. These features are not necessarly needed
> > on embedded systems. It allows to save ~11 Kb of kernel code and data:
> > 
> >    text	   data	    bss	    dec	    hex	filename
> > 1125436	 118764	 212992	1457192	 163c28	vmlinux.old
> > 1114299	 118564	 212992	1445855	 160fdf	vmlinux
> >  -11137    -200       0  -11337   -2C49 +/-
> > 
> > This patch has originally been written by Matt Mackall
> > <mpm@selenic.com>, and is part of the Linux Tiny project.
> > 
> > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> 
> In principle, I think this is a great idea.
> 
> >  config NFS_FS
> >  	tristate "NFS client support"
> > -	depends on INET
> > +	depends on INET && FILE_LOCKING
> >  	select LOCKD
> >  	select SUNRPC
> >  	select NFS_ACL_SUPPORT if NFS_V3_ACL
> 
> I think this part is a little lazy.  It should be possible to support
> NFS without file locking.  I suspect that's really not in-scope for the
> linux-tiny tree as currently envisaged with the focus on embedded
> devices that probably don't use NFS anyway.  Do we want to care about
> the situation of a machine with fixed workload, that doesn't need file
> locking, but does use NFS?

I would lean towards no, but if someone comes along who cares, they're
welcome to try it. This stuff all has to strike a balance between
savings and effort/complexity/maintainability, so any time the submitter
is too lazy to cover a less common use case, it's probably a good sign
they're approaching that tipping point. 

On the other hand, if you think it's trivial to do a locking-ectomy on
NFS, I'd be happy to see it.

The typical embedded NFS-based devices are NAS servers and media players
and are going to be more concerned about things like page cache
balancing.

-- 
Mathematics is the supreme nostalgia of our time.

Re: [patch 2/4] Configure out file locking features

[Jamie Lokier]

Matt Mackall wrote:
> The typical embedded NFS-based devices are NAS servers and media players
> and are going to be more concerned about things like page cache
> balancing.

Oh, those.

It would be really annoying to buy a home NAS and find it doesn't
support NFS locks or SMB oplocks.  NASes are vaguely useful for more
than one computer in the house at the same time.

That said, I bought a big, expensive one, found it far too slow for my
needs, send it back for a refund and bought a portable cheap USB disk
which had *so* much higher performance.  The convenience of serving
multiple machines just wasn't worth the lousy performance.

-- Jamie

Re: [patch 2/4] Configure out file locking features

[Adrian Bunk]

It seems the emails containing the patches never made it to the vger 
lists, which makes it a bit hard to comment on them.

Thomas, can you try to figure out what went wrong and resend them then?

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [patch 2/4] Configure out file locking features

[Thomas Petazzoni]

[-- Attachment #1: Type: text/plain, Size: 2070 bytes --]

Le Wed, 30 Jul 2008 17:27:54 +0300,
Adrian Bunk <bunk@kernel.org> a écrit :

> It seems the emails containing the patches never made it to the vger 
> lists, which makes it a bit hard to comment on them.

Yes, they didn't make it to the lists, for some reason. Maybe it's
because I sent them using "quilt mail --send", which uses my local
exim4 mail server, and for some reason, vger doesn't like that kind of
e-mails. However, my exim4 is configured to sent the e-mails through by
ISP SMTP. From my exim4 mainlog:

2008-07-29 17:47:57 1KNrQS-0007kt-Kg => linux-kernel@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> linux-embedded@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> netdev@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> davem@davemloft.net R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> mpm@selenic.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> akpm@linux-foundation.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> thomas.petazzoni@free-electrons.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> michael@free-electrons.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
2008-07-29 17:47:57 1KNrQS-0007kt-Kg Completed

So from my side, everything seemed to work well. Does anybody has a
clue ?

> Thomas, can you try to figure out what went wrong and resend them
> then?

I will send them again through my normal MUA, using quilt mail --mbox.
Hopefully it'll work.

Sincerly,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 189 bytes --]

Re: [patch 2/4] Configure out file locking features

[Uwe Kleine-König]

Hello Thomas,

Thomas Petazzoni wrote:
> Le Wed, 30 Jul 2008 17:27:54 +0300,
> Adrian Bunk <bunk@kernel.org> a écrit :
> 
> > It seems the emails containing the patches never made it to the vger 
> > lists, which makes it a bit hard to comment on them.
> 
> Yes, they didn't make it to the lists, for some reason. Maybe it's
> because I sent them using "quilt mail --send", which uses my local
> exim4 mail server, and for some reason, vger doesn't like that kind of
> e-mails. However, my exim4 is configured to sent the e-mails through by
> ISP SMTP. From my exim4 mainlog:
> 
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg => linux-kernel@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> linux-embedded@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> netdev@vger.kernel.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> davem@davemloft.net R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> mpm@selenic.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> akpm@linux-foundation.org R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> thomas.petazzoni@free-electrons.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg -> michael@free-electrons.com R=smarthost T=remote_smtp_smarthost H=smtp.free.fr [212.27.48.4]*
> 2008-07-29 17:47:57 1KNrQS-0007kt-Kg Completed
> 
> So from my side, everything seemed to work well. Does anybody has a
> clue ?
Don't know if this is the problem, but I had problems getting mails
through some time ago, too.  For me the problem was that the source
address was myusername@mymachine.intranet.$mycompany.$tld and
vger.kernel.org didn't want to take these because the host name had no
DNS entry.

I fixed that by rewriting the From line in outgoing mails on my host.
I'm using postfix (from Debian) so I had to add an entry to
/etc/postfix/sender_canonical.

Best regards
Uwe

-- 
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Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962
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[patch 1/4] Configure out AIO support

[Thomas Petazzoni]

[-- Attachment #1: configure-out-aio-support --]
[-- Type: text/plain, Size: 4663 bytes --]

This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:

   text	   data	    bss	    dec	    hex	filename
1115067	 119180	 217088	1451335	 162547	vmlinux
1108025	 119048	 217088	1444161	 160941	vmlinux.new
  -7042    -132       0   -7174   -1C06 +/-

This patch has been originally written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: bcrl@kvack.org
Cc: linux-aio@kvack.org
Cc: mpm@selenic.com
Cc: akpm@linux-foundation.org


---
 fs/Makefile         |    3 ++-
 include/linux/aio.h |    9 +++++++++
 init/Kconfig        |    8 ++++++++
 kernel/sys_ni.c     |    5 +++++
 kernel/sysctl.c     |    2 ++
 5 files changed, 26 insertions(+), 1 deletion(-)

Index: linuxdev/fs/Makefile
===================================================================
--- linuxdev.orig/fs/Makefile
+++ linuxdev/fs/Makefile
@@ -8,7 +8,7 @@
 obj-y :=	open.o read_write.o file_table.o super.o \
 		char_dev.o stat.o exec.o pipe.o namei.o fcntl.o \
 		ioctl.o readdir.o select.o fifo.o locks.o dcache.o inode.o \
-		attr.o bad_inode.o file.o filesystems.o namespace.o aio.o \
+		attr.o bad_inode.o file.o filesystems.o namespace.o \
 		seq_file.o xattr.o libfs.o fs-writeback.o \
 		pnode.o drop_caches.o splice.o sync.o utimes.o \
 		stack.o
@@ -27,6 +27,7 @@
 obj-$(CONFIG_SIGNALFD)		+= signalfd.o
 obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
+obj-$(CONFIG_AIO)               += aio.o
 obj-$(CONFIG_COMPAT)		+= compat.o compat_ioctl.o
 
 nfsd-$(CONFIG_NFSD)		:= nfsctl.o
Index: linuxdev/include/linux/aio.h
===================================================================
--- linuxdev.orig/include/linux/aio.h
+++ linuxdev/include/linux/aio.h
@@ -204,12 +204,21 @@
 /* prototypes */
 extern unsigned aio_max_size;
 
+#ifdef CONFIG_AIO
 extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
 extern int aio_put_req(struct kiocb *iocb);
 extern void kick_iocb(struct kiocb *iocb);
 extern int aio_complete(struct kiocb *iocb, long res, long res2);
 struct mm_struct;
 extern void exit_aio(struct mm_struct *mm);
+#else
+static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
+static inline int aio_put_req(struct kiocb *iocb) { return 0; }
+static inline void kick_iocb(struct kiocb *iocb) { }
+static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
+struct mm_struct;
+static inline void exit_aio(struct mm_struct *mm) { }
+#endif /* CONFIG_AIO */
 
 #define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
 
Index: linuxdev/init/Kconfig
===================================================================
--- linuxdev.orig/init/Kconfig
+++ linuxdev/init/Kconfig
@@ -724,6 +724,14 @@
 	  option replaces shmem and tmpfs with the much simpler ramfs code,
 	  which may be appropriate on small systems without swap.
 
+config AIO
+	bool "Enable AIO support" if EMBEDDED
+	default y
+	help
+	  This option enables POSIX asynchronous I/O which may by used
+          by some high performance threaded applications. Disabling
+          this option saves about 7k.
+
 config VM_EVENT_COUNTERS
 	default y
 	bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
Index: linuxdev/kernel/sys_ni.c
===================================================================
--- linuxdev.orig/kernel/sys_ni.c
+++ linuxdev/kernel/sys_ni.c
@@ -125,6 +125,11 @@
 cond_syscall(sys_vm86);
 cond_syscall(compat_sys_ipc);
 cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_io_setup);
+cond_syscall(sys_io_destroy);
+cond_syscall(sys_io_submit);
+cond_syscall(sys_io_cancel);
+cond_syscall(sys_io_getevents);
 
 /* arch-specific weak syscall entries */
 cond_syscall(sys_pciconfig_read);
Index: linuxdev/kernel/sysctl.c
===================================================================
--- linuxdev.orig/kernel/sysctl.c
+++ linuxdev/kernel/sysctl.c
@@ -1290,6 +1290,7 @@
 		.extra1		= &zero,
 		.extra2		= &two,
 	},
+#ifdef CONFIG_AIO
 	{
 		.procname	= "aio-nr",
 		.data		= &aio_nr,
@@ -1304,6 +1305,7 @@
 		.mode		= 0644,
 		.proc_handler	= &proc_doulongvec_minmax,
 	},
+#endif /* CONFIG_AIO */
 #ifdef CONFIG_INOTIFY_USER
 	{
 		.ctl_name	= FS_INOTIFY,

-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com

Re: [patch 1/4] Configure out AIO support

[Bernhard Fischer]

On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
>This patchs adds the CONFIG_AIO option which allows to remove support
>for asynchronous I/O operations, that are not necessarly used by
>applications, particularly on embedded devices. As this is a
>size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
>save ~7 kilobytes of kernel code/data:

Shouldn't this also make sure not to install aio_abi.h or at least an
empty aio_abi.h?

Re: [patch 1/4] Configure out AIO support

[Adrian Bunk]

On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> >This patchs adds the CONFIG_AIO option which allows to remove support
> >for asynchronous I/O operations, that are not necessarly used by
> >applications, particularly on embedded devices. As this is a
> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> >save ~7 kilobytes of kernel code/data:
> 
> Shouldn't this also make sure not to install aio_abi.h or at least an
> empty aio_abi.h?

The userspace headers are independent of any kernel configuration
(except for the architecture).

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [patch 1/4] Configure out AIO support

[Bernhard Fischer]

On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
>On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
>> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
>> >This patchs adds the CONFIG_AIO option which allows to remove support
>> >for asynchronous I/O operations, that are not necessarly used by
>> >applications, particularly on embedded devices. As this is a
>> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
>> >save ~7 kilobytes of kernel code/data:
>> 
>> Shouldn't this also make sure not to install aio_abi.h or at least an
>> empty aio_abi.h?
>
>The userspace headers are independent of any kernel configuration
>(except for the architecture).

I beg to disagree:
internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
the impl and it's users are interrested in it.

If a per package feature, independent of arch, is off, all respective
features stuff should be off for that particular installation.

I.e. if I, for subsequent installations, choose to turn on feature, the
requested feature-stuff will be installed properly. If I, OTOH, choose
to (keep to) turn off feature, then all feature-related stuff should --
and has to be and stay -- turned off.

In the particular case of the kernel exposing unwanted API extensions
that are off, all such API reminiscences should be off, thus not
installed to my staging dir at all since i explicitely asked for doing
away with all of the API.

From a libc POV i'd agree, but from an inherently broken userspace POV
installing willingly broken stuff is just wrong and misleading, imo.

Re: [patch 1/4] Configure out AIO support

[Adrian Bunk]

On Fri, Aug 01, 2008 at 12:42:22AM +0200, Bernhard Fischer wrote:
> On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
> >On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> >> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> >> >This patchs adds the CONFIG_AIO option which allows to remove support
> >> >for asynchronous I/O operations, that are not necessarly used by
> >> >applications, particularly on embedded devices. As this is a
> >> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> >> >save ~7 kilobytes of kernel code/data:
> >> 
> >> Shouldn't this also make sure not to install aio_abi.h or at least an
> >> empty aio_abi.h?
> >
> >The userspace headers are independent of any kernel configuration
> >(except for the architecture).
> 
> I beg to disagree:
> internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
> the impl and it's users are interrested in it.
>...

That's utter bullshit.

The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever 
change. [1]

cu
Adrian

[1] there are some exceptions like adding stuff (but not in existing 
    structs), but basically the contents of aio_abi.h is cast in stone

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

Re: [patch 1/4] Configure out AIO support

[Jamie Lokier]

Adrian Bunk wrote:
> On Fri, Aug 01, 2008 at 12:42:22AM +0200, Bernhard Fischer wrote:
> > On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote:
> > >On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote:
> > >> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote:
> > >> >This patchs adds the CONFIG_AIO option which allows to remove support
> > >> >for asynchronous I/O operations, that are not necessarly used by
> > >> >applications, particularly on embedded devices. As this is a
> > >> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
> > >> >save ~7 kilobytes of kernel code/data:
> > >> 
> > >> Shouldn't this also make sure not to install aio_abi.h or at least an
> > >> empty aio_abi.h?
> > >
> > >The userspace headers are independent of any kernel configuration
> > >(except for the architecture).
> > 
> > I beg to disagree:
> > internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
> > the impl and it's users are interrested in it.
> >...
> 
> That's utter bullshit.
> 
> The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever 
> change. [1]

Case in point:

I want to be able to compile an application for embedded Linux which
*can use* Linux-AIO, but can also run on a kernel which has Linux-AIO
removed by this patch.

I still want to compile the application with that capability, in case
it's run on another kernel with it enabled.

I shouldn't have to have a separate, special kernel with all options
enabled, just to compile applications that run on multiple kernels and
use run-time features when available.

Just like all the other kernel<->userspace interfaces, the header
files (including their presence) shouldn't depend on kernel
configuration at all.

-- Jamie

Re: [patch 1/4] Configure out AIO support

[Bernhard Fischer]

On Tue, Aug 05, 2008 at 07:26:07PM +0100, Jamie Lokier wrote:

>> > >The userspace headers are independent of any kernel configuration
>> > >(except for the architecture).
>> > 
>> > I beg to disagree:
>> > internals as exposed by e.g. aio_abi.h are impl dependent. Noone except
>> > the impl and it's users are interrested in it.
>> >...
>> 
>> That's utter bullshit.
>> 
>> The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever 
>> change. [1]
>
>Case in point:
>
>I want to be able to compile an application for embedded Linux which
>*can use* Linux-AIO, but can also run on a kernel which has Linux-AIO
>removed by this patch.
>
>I still want to compile the application with that capability, in case
>it's run on another kernel with it enabled.
>
>I shouldn't have to have a separate, special kernel with all options
>enabled, just to compile applications that run on multiple kernels and
>use run-time features when available.
>
>Just like all the other kernel<->userspace interfaces, the header
>files (including their presence) shouldn't depend on kernel
>configuration at all.

alright, makes perfect sense. I must have been playing too much with
libc recently, i guess.

thanks,