[libvirt] [PATCH] virprocess: Extend list of platforms for setns wrapper

[Martin Kletzander]

On Mon, Sep 15, 2014 at 04:22:18PM +0100, Daniel P. Berrange wrote:
>On Mon, Sep 15, 2014 at 05:20:46PM +0200, Michal Privoznik wrote:
>> On 15.09.2014 17:15, Martin Kletzander wrote:
>> >On Mon, Sep 15, 2014 at 03:43:55PM +0200, Michal Privoznik wrote:
>> >>Currently, the setns() wrapper is supported only for x86_64 and i686
>> >>which leaves us failing to build on other platforms like arm, aarch64
>> >>and so on. This means, that the wrapper needs to be extended to those
>> >>platforms and make to fail on runtime not compile time.
>> >>
>> >>The syscall numbers for other platforms was fetched using this
>> >>command:
>> >>
>> >>kernel.git $ git grep "define.*__NR_setns" | grep -e arm -e powerpc -e
>> >>s390
>> >>arch/arm/include/uapi/asm/unistd.h:#define
>> >>__NR_setns                   (__NR_SYSCALL_BASE+375)
>> >>arch/arm64/include/asm/unistd32.h:#define __NR_setns 375
>> >>arch/powerpc/include/uapi/asm/unistd.h:#define
>> >>__NR_setns               350
>> >>arch/s390/include/uapi/asm/unistd.h:#define __NR_setns          339
>> >>
>> >>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> >>---
>> >>src/util/virprocess.c | 18 ++++++++++++------
>> >>1 file changed, 12 insertions(+), 6 deletions(-)
>> >>
>> >
>> >NACK, we shouldn't be duplicating syscall definitions.  There should
>> >be AC_CHECK_FUNCS([setns]) (instead of AC_CHECK_FUNCS_ONCE() for the
>> >syscall) and having with_lxc = "yes" and ac_cv_func_setns != "yes"
>> >should result in an error.
>>
>> The only problem with this might be that on systems with older glibc (and
>> there is plenty of them) libvirt will fail to build / miss this feature. And
>> it's not that the kernel doesn't support the namesapces. But let me see if I
>> can get some ACKs on that approach you're suggesting.
>
>That's basically what the code did before we added the #define or NR_setns.
>We took the patch specifically to help Debian where the kernel has it but
>glibc is outdated.
>

Either Debian should patch their glibc or we should at lease use
SYS_setns IMHO.

>Regards,
>Daniel
>--
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