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Re: [RFC][PATCH 1/2] sparc32: Mark sendmsg and recvmsg system calls as unsupported
On 02/11/2016 09:35, Andreas Larsson wrote:
> On 2016-11-01 18:28, Adhemerval Zanella wrote:
>>
>>
>> On 01/11/2016 13:07, Andreas Larsson wrote:
>>> This fixes a bug introduced by abf29edd4a3918 that missed fixing up
>>> sparc32 in the change.
>>>
>>> * sysdeps/unix/sysv/linux/sparc/kernel-features.h: Undefine
>>> __ASSUME_SENDMSG_SYSCALL and __ASSUME_RECVMSG_SYSCALL for 32-bit
>>> sparcv8
>>> ---
>>> sysdeps/unix/sysv/linux/sparc/kernel-features.h | 4 +++-
>>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/sysdeps/unix/sysv/linux/sparc/kernel-features.h b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>>> index 69c9c7c..db3f5cd 100644
>>> --- a/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>>> +++ b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
>>> @@ -32,8 +32,10 @@
>>> #include_next <kernel-features.h>
>>>
>>> /* 32-bit SPARC kernels do not support
>>> - futex_atomic_cmpxchg_inatomic. */
>>> + futex_atomic_cmpxchg_inatomic or sendmsg/recvmsg. */
>>> #if !defined __arch64__ && !defined __sparc_v9__
>>> # undef __ASSUME_REQUEUE_PI
>>> # undef __ASSUME_SET_ROBUST_LIST
>>> +# undef __ASSUME_SENDMSG_SYSCALL
>>> +# undef __ASSUME_RECVMSG_SYSCALL
>>> #endif
>>>
>>
>> At least the kernel headers for Linux 3.2 on sparc defined both __NR_recvmsg
>> and __NR_sendmsg. Also, checking 'arch/sparc/kernel/sys32.S' on 3.2 does
>> seems that sparc32 have both recvmsg and sendmsg wire-up. Am I missing
>> something here?
>
> [resent to correct topic - I should apparently stay away from my mail client today]
>
> Linux kernel commit 8b30ca73b7cc7f2177cfc4e8274d2ebdba328cd5 added
> sys_sendmsg and sys_recvmsg to the sys_call_table in
> arch/sparc/kernel/systbls_32.S. So sparc32 kernels prior to Linux 4.4 do
> not support them as straight up system calls.
>
> Best regards,
> Andreas Larsson
Right, so it is advertise to userland through __SYS/__NR macros even though
it is not really supported?
Even though, I think a better solution would be:
/* All direct socketcalls are available only with kernel 4.4. */
#if __LINUX_KERNEL_VERSION < 0x040400
# undef __ASSUME_SENDMSG_SYSCALL
# undef __ASSUME_RECVMSG_SYSCALL
#endif