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Subject: Re: [RFC 05/10] x86/speculation: Add basic IBRS support
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To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Borislav Petkov <bp@suse.de>
CC:     Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        <linux-kernel@vger.kernel.org>, Andi Kleen <ak@linux.intel.com>,
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        Andy Lutomirski <luto@kernel.org>,
        "Arjan van de Ven" <arjan@linux.intel.com>,
        Ashok Raj <ashok.raj@intel.com>,
        "Asit Mallick" <asit.k.mallick@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "H . Peter Anvin" <hpa@zytor.com>,
        "Ingo Molnar" <mingo@redhat.com>,
        Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jun Nakajima <jun.nakajima@intel.com>,
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        <x86@kernel.org>
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Date:   Mon, 22 Jan 2018 13:36:59 +0000
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From:   "Woodhouse, David" <dwmw@amazon.co.uk>
Sender: linux-kernel-owner@vger.kernel.org
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On Mon, 2018-01-22 at 14:30 +0100, Greg Kroah-Hartman wrote:
> We kind of do, you can submit patches to UEFI, but I doubt that the
> processor-specific portions are actually present in the Tianocore code
> to be able to be patched.

This is just about which microcode your BIOS loads into the CPU before
booting the OS. It's not "process-specific portions in the Tianocore
code"; more a data blob =E2=80=94 just like when Linux updates microcode.

> What about LinuxBoot <https://linuxboot.org>, does it too take over too
> late in the boot process to control this?

Yes, I believe microcode updates are done in PEI which is before
LinuxBoot takes over.
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