Re: [PATCH} s390x sys32 duplicated code cleanup (was [PATCH RFC] s390x sys32...)

[Tim Hockin <thockin@sun.com>]

Tim Hockin wrote:
> Martin Schwidefsky wrote:
> 
>>> It seems to me that if we do:
>>> * s390x defines CONFIG_UID16
>>> * typedef __kernel_old_gid_t to u16
>>> * get rid of all the sys32_*16 stuff and just call the uid16.c function
>>
>>
>> I checked the code and didn't find any reason why this shouldn't work.
>> In fact with the 31 bit emulation layer the 64 bit kernel does need the
>> 16 bit uid/gid system calls although only for the emulation. To make it
>> really perfect you could define CONFIG_UID16 dependent on
>> CONFIG_S390_SUPPORT. This saves a few bytes in the image if the emulation
>> support is not enabled.

Uggh, DaveM pointed out a very good issue with this fix (similar for 
Sparc64) and core files.  Core files will now have truncated uid/gid 
values because fs/binfmt_elf calls NEW_TO_OLD_UID().  May be other 
places, too.

I guess you should not apply this patch until I've had a better think 
about it.

Tim




-- 
Tim Hockin
Systems Software Engineer
Sun Microsystems, Linux Kernel Engineering
thockin@sun.com