Re: [PATCH] powerpc: Enable demuxed sysv IPC syscalls

["Paul E. Murphy" <murphyp at linux dot vnet dot ibm dot com>]

On 12/03/2015 05:13 PM, Arnd Bergmann wrote:
> On Friday 04 December 2015 00:09:08 Arnd Bergmann wrote:
>> On Thursday 03 December 2015 23:12:10 Andreas Schwab wrote:
>>>>  #endif
>>>> @@ -64,7 +68,12 @@ compat_symbol (libc, __old_msgctl, msgctl, GLIBC_2_0);
>>>>  int
>>>>  __new_msgctl (int msqid, int cmd, struct msqid_ds *buf)
>>>>  {
>>>> +#ifdef __ASSUME_MSGCTL_SYSCALL
>>>> +  return INLINE_SYSCALL (msgctl, 3, msqid, cmd | __IPC_64, buf);
>>>
>>> Why does a brand new syscall need IPC_64?
>>
>> This is a bug in the kernel, which we should fix there.  The same
>> problem currently exists on ARM and AVR32, which also support the
>> old IPC API (pre-__IPC64) and are adding separate syscalls now.
> 
> Correction, I looked at the wrong place: ARM and AVR32 have had this
> problem for a long time, so we can't fix it any more. But we should
> fix it for PowerPC and all other architectures that add these calls
> in the future.

I'm not clear as to what you are suggesting for this patch. Looking at the
kernel code, it does not look trivial to remove the IPC_64 bit. It seems
to boil down to whether ARCH_WANT_IPC_PARSE_VERSION is configured on the
kernel.

Should the compat versions of these be left untouched? Or is it safe to
switch them to the demuxed version?

> 	Arnd
>