From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@alien8.de>
Cc: X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH 2/5 -v2.1] x86: Detect CPUID support early at boot
Date: Sun, 10 Feb 2013 07:10:56 -0800 [thread overview]
Message-ID: <168505a3-2aba-4d4a-b1e7-d37c79ae306c@email.android.com> (raw)
In-Reply-To: <20130210083616.GA4878@pd.tnic>
Sure it does... it takes time.
Borislav Petkov <bp@alien8.de> wrote:
>On Sat, Feb 09, 2013 at 08:34:53PM -0800, H. Peter Anvin wrote:
>> I wouldn't really call it a "side effect". Perhaps the right thing
>> here is to say something like "we want to start out with %eflags
>> unambiguously clear".
>>
>> (Note also we have had to CLD earlier because we have already copied
>> the command line.)
>
>Ok, let's make it even more verbose so that people know in the future:
>
>"... we want to start out with EFLAGS unambiguously clear. That means
>DF
>in particular (even though we have cleared it earlier after copying the
>command line) because GCC expects it."
>
>How does that sound?
>
>Also, I was wondering about the whole reasoning behind that: do you
>know
>why DF=0 is a GCC requirement? I mean, nothing hurts GCC from issuing a
>CLD each time?
>
>Thanks.
--
Sent from my mobile phone. Please excuse brevity and lack of formatting.
prev parent reply other threads:[~2013-02-10 15:12 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-09 19:52 [PATCH 0/5] x86, head_32: Some cleanups, -v2 Borislav Petkov
2013-02-09 19:52 ` [PATCH 1/5] x86, head_32: Remove i386 pieces Borislav Petkov
2013-02-09 19:52 ` [PATCH 2/5] x86: Detect CPUID support early at boot Borislav Petkov
2013-02-09 19:52 ` [PATCH 3/5] x86, head_32: Remove second CPUID detection from default_entry Borislav Petkov
2013-02-09 19:52 ` [PATCH 4/5] x86, head_32: Give the 6 label a real name Borislav Petkov
2013-02-09 19:52 ` [PATCH 5/5] x86, head_32: Remove an old gcc2 fix Borislav Petkov
2013-02-09 20:51 ` H. Peter Anvin
2013-02-09 20:52 ` H. Peter Anvin
2013-02-09 21:23 ` Borislav Petkov
2013-02-09 22:08 ` [PATCH 5/5 -v2] x86, head_32: Clear DF much earlier Borislav Petkov
2013-02-09 22:23 ` [PATCH 5/5] x86, head_32: Remove an old gcc2 fix H. Peter Anvin
2013-02-09 23:13 ` Borislav Petkov
2013-02-09 23:16 ` [PATCH 2/5 -v2.1] x86: Detect CPUID support early at boot Borislav Petkov
2013-02-10 4:34 ` H. Peter Anvin
2013-02-10 8:36 ` Borislav Petkov
2013-02-10 15:10 ` H. Peter Anvin [this message]
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