From: Kip Macy <kip.macy@gmail.com>
To: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
Cc: xen-devel <xen-devel@lists.xensource.com>
Subject: Re: Is there a way to add GDT entries without having a second page?
Date: Fri, 6 May 2005 08:31:19 -0700 [thread overview]
Message-ID: <b1fa2917050506083170c2bd8e@mail.gmail.com> (raw)
In-Reply-To: <a7431edea2d8177eae1441c7a85d7c6b@cl.cam.ac.uk>
On 5/5/05, Keir Fraser <Keir.Fraser@cl.cam.ac.uk> wrote:
>
> On 6 May 2005, at 01:50, Kip Macy wrote:
>
> > I can add entries incrementally to the GDT by having a second page
> > frame lying around copying from the current one to the unused one and
> > then switching between them for updates, but is there a more elegant
> > way?
>
> What's the problem? You want a 'writable GDT'? This is very doable
> since we have the emulator, but in Linux it was not hard to patch the
> places that write to the GDT to do a hypercall instead.
Each cpu in its initialization sequence adds additional entries to the
GDT. The pcpu data area is referenced through %fs, much like TLS. It
occurred to me after I had already asked the question that I could
just have the boot processor add the entries for all the CPUs so there
wouldn't be the need for any additional updates.
prev parent reply other threads:[~2005-05-06 15:31 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-06 0:50 Is there a way to add GDT entries without having a second page? Kip Macy
2005-05-06 6:10 ` Keir Fraser
2005-05-06 15:31 ` Kip Macy [this message]
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