All of lore.kernel.org
 help / color / mirror / Atom feed
From: Borislav Petkov <bp@alien8.de>
To: "H. Peter Anvin" <hpa@zytor.com>
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 09:36:16 +0100	[thread overview]
Message-ID: <20130210083616.GA4878@pd.tnic> (raw)
In-Reply-To: <5117236D.5000607@zytor.com>

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.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

  reply	other threads:[~2013-02-10  8:36 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 [this message]
2013-02-10 15:10                 ` H. Peter Anvin

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20130210083616.GA4878@pd.tnic \
    --to=bp@alien8.de \
    --cc=bp@suse.de \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.