From: ebiederm@xmission.com (Eric W. Biederman)
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexander van Heukelum <heukelum@mailshack.com>,
"Antonino A. Daplas" <adaplas@gmail.com>, Andi Kleen <ak@suse.de>,
Andrew Morton <akpm@osdl.org>, Matt Domsch <Matt_Domsch@dell.com>,
Vivek Goyal <vgoyal@in.ibm.com>,
James Bottomley <James.Bottomley@HansenPar>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: x86 setup rewrite tree ready for flamage^W review
Date: Sat, 12 May 2007 16:04:27 -0600 [thread overview]
Message-ID: <m1iraxr95g.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <46460E9E.9020308@zytor.com> (H. Peter Anvin's message of "Sat, 12 May 2007 11:59:42 -0700")
"H. Peter Anvin" <hpa@zytor.com> writes:
> Eric W. Biederman wrote:
>>
>> Even on 386 and 486 class cpus?
>>
>
> Yes, even on 386 and 486 class CPUs. I have personally tested this on
> machines as old as the original "double sigma" 386-16.
Ok. If you have tested on a wide variety of machines then I won't
worry about it.
I guess if a cr0 write has always been synchronizing things should be
a safe practice. The practical danger is if you write to cr0 and the
pipeline is not flushed and the segment loads might execute as 16bit
mode segment register loads. I think this is more of a 486 or 586/Pentium
danger actually then a 386 one.
Hmm. I'm not certain about enabling protected mode but enabling paging
at least does appear to be documented to require a jump, before the P6
core. Which may be why it is recommended for initializing protected
mode.
Eric
next prev parent reply other threads:[~2007-05-12 22:05 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-09 5:15 H. Peter Anvin
2007-05-09 6:51 ` Sam Ravnborg
2007-05-09 7:02 ` H. Peter Anvin
2007-05-09 8:11 ` Sam Ravnborg
2007-05-10 14:10 ` Alexander van Heukelum
2007-05-10 18:08 ` H. Peter Anvin
2007-05-10 18:38 ` Martin Mares
2007-05-11 0:55 ` H. Peter Anvin
2007-05-10 22:04 ` Alexander van Heukelum
2007-05-10 22:48 ` H. Peter Anvin
2007-05-12 12:21 ` Alexander van Heukelum
2007-05-12 14:20 ` Eric W. Biederman
2007-05-12 18:09 ` H. Peter Anvin
2007-05-12 18:35 ` Eric W. Biederman
2007-05-12 18:59 ` H. Peter Anvin
2007-05-12 22:04 ` Eric W. Biederman [this message]
2007-05-12 22:08 ` H. Peter Anvin
2007-05-11 4:37 ` Vivek Goyal
2007-05-11 23:58 ` Kevin Winchester
2007-05-12 0:23 ` H. Peter Anvin
2007-05-13 0:35 ` Kevin Winchester
2007-05-15 20:45 ` Rob Landley
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