From: Keir Fraser <keir.fraser@eu.citrix.com>
To: Jan Beulich <JBeulich@novell.com>,
Ian Campbell <Ian.Campbell@eu.citrix.com>
Cc: "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
Subject: Re: Re: [PATCH] switch to a known good/static GDT beforekexec
Date: Thu, 02 Jul 2009 13:38:08 +0100 [thread overview]
Message-ID: <C67268C0.885D%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <4A4CB9EC020000780000897E@vpn.id2.novell.com>
On 02/07/2009 12:45, "Jan Beulich" <JBeulich@novell.com> wrote:
>>>> Keir Fraser <keir.fraser@eu.citrix.com> 02.07.09 13:11 >>>
>> I have one more question then -- when need_full_gdt(n), why do we always
>> unconditionally rewrite the l1es mapping the reserved gdt entries? Shouldn't
>> that be done on vcpu creation only and perhaps on compat mode switch (i.e.,
>> isn't it wasteful to do it in the context switch path)?
>
> While that's correct, we're talking about a single memory write here (plus
> the setup code), which I think is no more wasteful than adding the extra
> checking that would be needed to see whether we switch between
> compat and !compat (including the !need_full_gdt(p) case, where we
> don't know what kind of mapping we currently have).
Hm yes, fair enough.
-- Keir
next prev parent reply other threads:[~2009-07-02 12:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-02 8:45 [PATCH] switch to a known good/static GDT before kexec Ian Campbell
2009-07-02 9:18 ` Keir Fraser
2009-07-02 10:52 ` Keir Fraser
2009-07-02 11:11 ` Keir Fraser
2009-07-02 11:45 ` Re: [PATCH] switch to a known good/static GDT beforekexec Jan Beulich
2009-07-02 12:38 ` Keir Fraser [this message]
2009-07-02 19:59 ` Keir Fraser
2009-07-03 7:15 ` Re: [PATCH] switch to a known good/static GDTbeforekexec Jan Beulich
2009-07-03 7:48 ` Keir Fraser
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