Subject: Re: [PATCH v3 0/4] xfrm: add x86 CONFIG_COMPAT support

From: Patrick McHardy <[email-masked]>
Date: Thu, 08 Apr 2010 11:44:43 +0200

David Miller wrote:
> From: Patrick McHardy <[email-masked]>
> Date: Wed, 07 Apr 2010 15:45:51 +0200
> 
>> Florian Westphal wrote:
>>> David Miller <[email-masked]> wrote:
>>>> From: Florian Westphal <[email-masked]>
>>>> Date: Tue,  6 Apr 2010 00:27:07 +0200
>>> [..]
>>>
>>>>> I sent a patch that solved this by adding a sys_compat_write syscall
>>>>> and a ->compat_aio_write() to struct file_operations to the
>>>>> vfs mailing list, but that patch was ignored by the vfs people,
>>>>> and the x86 folks did not exactly like the idea either.
>>>>>
>>>>> So this leaves three alternatives:
>>>>> 1 - drop the whole idea and keep the current status.
>>>>> 2 - Add new structure definitions (with new numbering) that would work
>>>>>     everywhere, keep the old ones for backwards compatibility (This
>>>>>     was suggested by Arnd Bergmann).
>> Given that there is only a quite small number of users of this
>> interface, that would in my opinion be the best way.
> 
> Can you explain that line of reasoning?
> 
> It's not that there are only "3 or 4 tools" using these interfaces,
> it's the fact that 32-bit binaries of those tools are on millions and
> millions of systems out there.

Yeah, but they're currently not working if used on 64 bit hosts,
so I don't think its unreasonable to consider just the number of
tools that need to be fixed. Either the kernel or the userspace
programs have to be updated either way.