Re: [PATCH 2/2] x86_64,signal: Remove 'fs' and 'gs' from sigcontext

From: H. Peter Anvin
Date: Fri Jul 11 2014 - 22:09:30 EST


On 07/11/2014 11:39 AM, Andy Lutomirski wrote:
> On Fri, Jul 11, 2014 at 11:12 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>>> diff --git a/arch/x86/include/uapi/asm/sigcontext.h b/arch/x86/include/uapi/asm/sigcontext.h
>>> index 076b11f..df9908b 100644
>>> --- a/arch/x86/include/uapi/asm/sigcontext.h
>>> +++ b/arch/x86/include/uapi/asm/sigcontext.h
>>
>> I don't think renaming fields in uapi/asm is acceptable. These
>> are likely used by user programs and you'll break compiles.
>
> Hmm. That's a fair point. On the other hand, any user code that uses
> these fields explicitly may already be broken, since the current names
> of these fields rather strongly imply that they do something.
>
> Is there any clear policy on minor API breaks in the UAPI headers that
> don't affect ABI?
>

There really isn't, and this *definitely* a boundary case: as you state,
it is very likely that anyone currently using them are doing so
incorrectly, but it does induce potential source-level breakage.

Linus, do you have any guidance here?

-hpa

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