linux-kernel - Re: [PATCH 0/3] x86: make rsdp address accessible via boot params

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Date:   Tue, 28 Nov 2017 22:03:15 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Juergen Gross <jgross@...e.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        xen-devel@...ts.xenproject.org,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH 0/3] x86: make rsdp address accessible via boot params

On Tue, Nov 28, 2017 at 10:43 AM, Juergen Gross <jgross@...e.com> wrote:
> In the non-EFI boot path the ACPI RSDP table is currently found via
> either EBDA or by searching through low memory for the RSDP magic.
> This requires the RSDP to be located in the first 1MB of physical
> memory. Xen PVH guests, however, get the RSDP address via the start of
> day information block.
>
> In order to support an arbitrary RSDP address this patch series adds
> the physical address of the RSDP to the boot params structure filled
> by the boot loader. A kernel booted directly in PVH mode can save the
> RSDP address in the boot params, while a kernel booted in PVH mode via
> grub can rely on the RSDP address being specified by grub2 (which in
> turn got the address via the start of day information block from Xen).
>
> Juergen Gross (3):
>   x86/boot: add acpi rsdp address to setup_header
>   x86/acpi: take rsdp address for boot params if available
>   x86/xen: supply rsdp address in boot params for pvh guests
>
>  Documentation/x86/boot.txt            | 19 +++++++++++++++++++
>  arch/x86/boot/header.S                |  6 +++++-
>  arch/x86/include/uapi/asm/bootparam.h |  1 +
>  arch/x86/xen/enlighten_pvh.c          |  2 ++
>  drivers/acpi/osl.c                    |  8 ++++++++
>  5 files changed, 35 insertions(+), 1 deletion(-)
>
> --

Is this going to work with all existing setups?

Thanks,
Rafael