From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>, Keir Fraser <keir@xen.org>
Subject: Re: [PATCH] x86/boot: Use mov to cr0 in preference to lmsw
Date: Wed, 28 Aug 2013 11:33:15 +0100 [thread overview]
Message-ID: <521DD1EB.7050502@citrix.com> (raw)
In-Reply-To: <521DEB8602000078000EF07E@nat28.tlf.novell.com>
On 28/08/13 11:22, Jan Beulich wrote:
>>>> On 28.08.13 at 12:05, Andrew Cooper <andrew.cooper3@citrix.com> wrote:
>> lmsw is for compability for 286 processors only, and any more modern
>> processors are recomended to use mov to cr0. Xen has never been capable of
>> booting on a 286, given its multiboot entry.
> I don't really mind this part (albeit it results in growth of the
> trampoline code), but ...
>
>> Furthermore, this avoids needless playing with the CD, NW and AM bits.
>> These do get explicitly chosen slightly later on boot.
> ... I clearly don't understand what you're referring to here: These
> bits don't get modified by LMSW.
>
> Jan
>
D'oh - yes. I intended the MP, EM and TS bits. (I scanned the wrong
direction through the written description of the cr0 bits). The
I shall send v2 which corrects the description - it is a bit too
misleading as it currently stands.
next prev parent reply other threads:[~2013-08-28 10:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-28 10:05 [PATCH] x86/boot: Use mov to cr0 in preference to lmsw Andrew Cooper
2013-08-28 10:22 ` Jan Beulich
2013-08-28 10:33 ` Andrew Cooper [this message]
2013-08-28 10:36 ` [Patch v2] " Andrew Cooper
2013-08-28 12:54 ` Keir Fraser
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