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Date:   Thu, 30 Aug 2018 20:46:39 +0200
From:   Joerg Roedel <>
To:     Linus Torvalds <>
Cc:     Guenter Roeck <>,
        Linux Kernel Mailing List <>,
        Thomas Gleixner <>,
        Michal Hocko <>,
        Andi Kleen <>,
        the arch/x86 maintainers <>,
        Dave Hansen <>,
        Pavel Machek <>
Subject: Re: efi boot failures due to PTI with 32 bit builds and Intel CPUs

On Thu, Aug 30, 2018 at 11:21:49AM -0700, Linus Torvalds wrote:
> On Thu, Aug 30, 2018 at 11:08 AM Joerg Roedel <> wrote:
> >
> > Without a mapped GDT the #PF and #DF handlers also can't be started, so
> > the machine triple-faults. Below diff fixes it for me, I'll send a
> > proper patch tomorrow.
> Hmm. Is there any reason why this code doesn't just use
>         load_fixmap_gdt(0);

No idea, probably the function didn't exist when the code was written?
I can change that when writing the patch.

> and shouldn't it do it after loading the new %cr3?

That seems more robust, yes. No sure if the old %cr3
(initial_page_table) has the fixmap gdt mapped at all.


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