linux-kernel - Re: [PATCH v3 1/2] Documentation/driver-api/cxl: BIOS/EFI expectation update

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <9be1e001-2fd9-4da8-b602-4ac55002888e@amd.com>
Date: Sat, 20 Dec 2025 06:53:48 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Gregory Price <gourry@...rry.net>, linux-cxl@...r.kernel.org
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel-team@...a.com, dave@...olabs.net, jonathan.cameron@...wei.com,
 dave.jiang@...el.com, alison.schofield@...el.com, vishal.l.verma@...el.com,
 ira.weiny@...el.com, dan.j.williams@...el.com, corbet@....net,
 rakuram.e96@...il.com
Subject: Re: [PATCH v3 1/2] Documentation/driver-api/cxl: BIOS/EFI expectation
 update


On 12/19/25 17:05, Gregory Price wrote:
> Add a snippet about what Linux expects BIOS/EFI to do (and not
> to do) to the BIOS/EFI section.
>
> Suggested-by: Alejandro Lucero Palau <alucerop@....com>
> Signed-off-by: Gregory Price <gourry@...rry.net>


Reviewed-by: Alejandro Lucero Palau <alucerop@....com>


> ---
>   .../driver-api/cxl/platform/bios-and-efi.rst  | 20 +++++++++++++++++++
>   1 file changed, 20 insertions(+)
>
> diff --git a/Documentation/driver-api/cxl/platform/bios-and-efi.rst b/Documentation/driver-api/cxl/platform/bios-and-efi.rst
> index a9aa0ccd92af..9034c206cf8e 100644
> --- a/Documentation/driver-api/cxl/platform/bios-and-efi.rst
> +++ b/Documentation/driver-api/cxl/platform/bios-and-efi.rst
> @@ -29,6 +29,26 @@ at :doc:`ACPI Tables <acpi>`.
>      on physical memory region size and alignment, memory holes, HDM interleave,
>      and what linux expects of HDM decoders trying to work with these features.
>   
> +
> +Linux Expectations of BIOS/EFI Software
> +=======================================
> +Linux expects BIOS/EFI software to construct sufficient ACPI tables (such as
> +CEDT, SRAT, HMAT, etc) and platform-specific configurations (such as HPA spaces
> +and host-bridge interleave configurations) to allow the Linux driver to
> +subsequently configure the devices in the CXL fabric at runtime.
> +
> +Programming of HDM decoders and switch ports is not required, and may be
> +deferred to the CXL driver based on admin policy (e.g. udev rules).
> +
> +Some platforms may require pre-programming HDM decoders and locking them
> +due to quirks (see: Zen5 address translation), but this is not the normal,
> +"expected" configuration path.  This should be avoided if possible.
> +
> +Some platforms may wish to pre-configure these resources to bring memory
> +up without requiring CXL driver support.  These platform vendors should
> +test their configurations with the existing CXL driver and provide driver
> +support for their auto-configurations if features like RAS are required.
> +
>   UEFI Settings
>   =============
>   If your platform supports it, the :code:`uefisettings` command can be used to