linux-kernel - Re: [PATCH 0/5] x86: IA32 emulation cleanups

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Message-ID: <CAMzpN2ik2R_402PxWKPhAF95hQ=XTqY9TJsz4-+EKWFhJkSwrg@mail.gmail.com>
Date:	Wed, 4 Mar 2015 01:22:09 -0500
From:	Brian Gerst <brgerst@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	"the arch/x86 maintainers" <x86@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 0/5] x86: IA32 emulation cleanups

On Wed, Mar 4, 2015 at 12:24 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Brian Gerst <brgerst@...il.com> wrote:
>
>> This series cleans up some files in the 32-bit emulation code, by merging
>> with the native 32-bit code, or in the case of the syscall audit, using the
>> generic compat code that was recently added.
>>
>> Brian Gerst (5):
>>   x86: Remove compat_ni_syscall()
>>   x86: Merge native and compat 32-bit syscall tables
>>   x86: Remove sys32_vm86_warning
>>   x86: Use generic compat audit code
>>   x86: Clean up ia32/Makefile
>
> So this series is looking pretty good to me, I've picked up #1-#3,
> pending clarification on #4. I've stuck them into tip:x86/asm, because
> they might interact with ongoing system call entry work.
>
> While we are at it: CONFIG_IA32_EMULATION is a misnomer: there's
> nothing 'emulated' there, it's full software and hardware support for
> the 32-bit ABI. It's just an ugly (and somewhat confusing) replacement
> for CONFIG_COMPAT that most other architectures are using.
>
> So could we also get rid of CONFIG_IA32_EMULATION and change most of
> its uses over to CONFIG_COMPAT et al? The only complication with that
> might be that IA32_EMULATION kconfig switch hardcodes a few features
> currently:
>
>         select BINFMT_ELF
>         select COMPAT_BINFMT_ELF
>         select HAVE_UID16
>
> allowing the binfmt formats to be undefined should be OK; the uid16
> dependency needs to be checked, whether it's safe to allow it to be
> disabled.
>
> Thanks,
>
>         Ingo

It looks like most cases can simply be replaced.  There are some
subtle relations with the x32 ABI though, and that will take some time
to sort out.

--
Brian Gerst
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