Linux ARM with XZ compression issue

Linux ARM with XZ compression issue

[Marek Vasut]

Hello,

I'm seeing the following issue when building arm linux kernel compressed with XZ 
compression:

  XZKERN  arch/arm/boot/compressed/piggy.xzkern
  CC      arch/arm/boot/compressed/decompress.o
In file included from include/linux/kernel.h:23:0,
                 from 
arch/arm/boot/compressed/../../../../lib/xz/xz_private.h:15,
                 from 
arch/arm/boot/compressed/../../../../lib/decompress_unxz.c:145,
                 from arch/arm/boot/compressed/decompress.c:50:
include/linux/dynamic_debug.h: In function ?ddebug_dyndbg_module_param_cb?:
include/linux/dynamic_debug.h:111:2: error: implicit declaration of function 
?strstr? [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[2]: *** [arch/arm/boot/compressed/decompress.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [arch/arm/boot/compressed/vmlinux] Error 2
make: *** [uImage] Error 2

This is because ARM doesn't implement strstr() in the decompressor phase. Newly 
added strstr() in include/linux/dynamic_debug.h triggers the issue:

b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 108) static inline int 
ddebug_dyndbg_module_param_cb(char *param, char *val,
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 109)                                                
const char *modname)
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 110) {
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 111)        if 
(strstr(param, "dyndbg")) {
516cf1be (Jim Cromie      2012-05-01 05:23:12 -0600 112)                /* avoid 
pr_warn(), which wants pr_fmt() fully defined */
516cf1be (Jim Cromie      2012-05-01 05:23:12 -0600 113)                
printk(KERN_WARNING "dyndbg param is supported only in "
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 114)                        
"CONFIG_DYNAMIC_DEBUG builds\n");
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 115)                return 
0; /* allow and ignore */
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 116)        }
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 117)        return -EINVAL;
b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 118) }

What do you suggest please? Implement strstr() for ARM into 
arch/arm/kernel/compressed/string.c maybe? I checked into the GLIBC strstr() 
implementation, though that seems quite complex for this purpose.

Best regards,
Marek Vasut

Linux ARM with XZ compression issue

[Marek Vasut]

Dear Jim Cromie,

> hi Marek,
> 
> Surprising problem - is strstr the only one missing ?

I think so.

> Its only used in the stub fn, so you could cheat and
> just return 0, or warn less discriminately and return 0.
> Obviously, that wouldnt be acceptable for mainline.

Correct, so I'm looking for proper solution.

> What happens if you build with compression other than XZ ?

LZMA is good, GZ as well.

> is it specific to XZ as you said, or a more general problem ?

Specific to XZ.

> On Wed, Jul 18, 2012 at 8:34 AM, Marek Vasut <marex@denx.de> wrote:
> > Hello,
> > 
> > I'm seeing the following issue when building arm linux kernel compressed
> > with XZ
> > 
> > compression:
> >   XZKERN  arch/arm/boot/compressed/piggy.xzkern
> >   CC      arch/arm/boot/compressed/decompress.o
> > 
> > In file included from include/linux/kernel.h:23:0,
> > 
> >                  from
> > 
> > arch/arm/boot/compressed/../../../../lib/xz/xz_private.h:15,
> > 
> >                  from
> > 
> > arch/arm/boot/compressed/../../../../lib/decompress_unxz.c:145,
> > 
> >                  from arch/arm/boot/compressed/decompress.c:50:
> > include/linux/dynamic_debug.h: In function
> > ?ddebug_dyndbg_module_param_cb?: include/linux/dynamic_debug.h:111:2:
> > error: implicit declaration of function ?strstr?
> > [-Werror=implicit-function-declaration]
> > cc1: some warnings being treated as errors
> > make[2]: *** [arch/arm/boot/compressed/decompress.o] Error 1
> > make[2]: *** Waiting for unfinished jobs....
> > make[1]: *** [arch/arm/boot/compressed/vmlinux] Error 2
> > make: *** [uImage] Error 2
> > 
> > This is because ARM doesn't implement strstr() in the decompressor phase.
> > Newly added strstr() in include/linux/dynamic_debug.h triggers the
> > issue:
> > 
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 108) static inline
> > int ddebug_dyndbg_module_param_cb(char *param, char *val,
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 109)
> > const char *modname)
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 110) {
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 111)        if
> > (strstr(param, "dyndbg")) {
> > 516cf1be (Jim Cromie      2012-05-01 05:23:12 -0600 112)               
> > /* avoid pr_warn(), which wants pr_fmt() fully defined */
> > 516cf1be (Jim Cromie      2012-05-01 05:23:12 -0600 113)
> > printk(KERN_WARNING "dyndbg param is supported only in "
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 114)
> > "CONFIG_DYNAMIC_DEBUG builds\n");
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 115)               
> > return 0; /* allow and ignore */
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 116)        }
> > b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 117)        return
> > -EINVAL; b48420c1 (Jim Cromie      2012-04-27 14:30:35 -0600 118) }
> > 
> > What do you suggest please? Implement strstr() for ARM into
> > arch/arm/kernel/compressed/string.c maybe? I checked into the GLIBC
> > strstr() implementation, though that seems quite complex for this
> > purpose.
> > 
> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut

Linux ARM with XZ compression issue

[Marek Vasut]

Dear Jim Cromie,

Note, try keeping the CC list please

> hi again,
> 
> On Wed, Jul 18, 2012 at 4:24 PM, Marek Vasut <marex@denx.de> wrote:
> > Dear Jim Cromie,
> > 
> >> hi Marek,
> >> 
> >> Surprising problem - is strstr the only one missing ?
> > 
> > I think so.
> > 
> >> Its only used in the stub fn, so you could cheat and
> >> just return 0, or warn less discriminately and return 0.
> >> Obviously, that wouldnt be acceptable for mainline.
> > 
> > Correct, so I'm looking for proper solution.
> 
> Ok.  I think youre on the right track - ie adding the fn.
> 
> just one more thought -
> add a strcmp call into the func, see if it compiles or breaks
> the same way.  If it breaks, theres a larger build issue,
> and Im not sure how LKML would react.

Hm, looks like strcmp is also missing, even though it's declared in

arch/arm/boot/compressed/string.c

> >> What happens if you build with compression other than XZ ?
> > 
> > LZMA is good, GZ as well.
> 
> ok, thats good -
> It suggests the problem is quite localized.
> 
> I suppose strcmp could still be missing,
> and possibly more likely, since the issue is so localized,
> and not exposed by other builds in other arches.
> 
> Do you already know where strstr should be added ?

arch/arm/boot/compressed/string.c I believe.

> Im asking cuz Im completely unfamiliar with arm,
> but did recently buy a raspberry-PI, so I'll be starting
> to hack on that eventually :-)
> 
> >> is it specific to XZ as you said, or a more general problem ?
> > 
> > Specific to XZ.
> > 

[...]

Best regards,
Marek Vasut