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Re: [PATCH 3/4] Consolidate pread/pread64 implementations

On 05-01-2016 17:11, Mike Frysinger wrote:
> On 05 Jan 2016 10:49, Adhemerval Zanella wrote:
>> On 04-01-2016 22:53, Mike Frysinger wrote:
>>> On 04 Jan 2016 10:42, Adhemerval Zanella wrote:
>>>> On 29-12-2015 15:28, Mike Frysinger wrote:
>>>>> On 18 Nov 2015 12:02, Adhemerval Zanella wrote:
>>>>>> This patch consolidates all the pread/pread64 implementation for Linux
>>>>>> in only one (sysdeps/unix/sysv/linux/pread.c).  It also removes the
>>>>>> syscall from the auto-generation using assembly macros.
>>>>>> For pread{64} offset argument placement the new SYSCALL_LL{64} macro
>>>>>> is used.  For pread ports that do not define __NR_pread will use
>>>>>> __NR_pread64 and for pread64 ports that dot define __NR_pread64 will
>>>>>> use __NR_pread for the syscall.
>>>>> pretty sure you just broke sh here.  while it doesn't have the 64-bit
>>>>> arg alignment issue, it has a wart where it copied the kernel interface
>>>>> of one.  you can see it in the files you deleted:
>>>> Indeed, my understanding is SH also requires __ASSUME_ALIGNED_REGISTER_PAIRS.
>>>> I will change it for the 1/4 patch part.
>>> just to be clear, SuperH (the ABI) does not have these 64-bit register
>>> pair requirements like ARM/EABI.  its syscall ABI for pread64/pwrite64
>>> has legacy cruft where there's a dummy reg before the 64-bit value.  so
>>> you can (and want) to use the same logic just for these two syscalls as
>>> the result happens to look the same.
>> Right, so for SuperH kernel interface the 64-bit pair cruft is only for
>> pread64/pwrite64 or is it for all 64-bits arguments?
> just pread64/pwrite64:
> -mike

sigh... so __ASSUME_ALIGNED_REGISTER_PAIRS is not the way to go on SH. I 
would prefer to avoid this, but since kernel interface is what it is I
think for SH it would be better to provide specific implementations.
I will change that, thanks for the information.

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