From: Vincent Mailhol <mailhol@kernel.org>
To: Ard Biesheuvel <ardb+git@google.com>, linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
x86@kernel.org
Subject: Re: [PATCH v2 10/10] efi/libstub: add initial Boot Loader Interface support
Date: Tue, 15 Sep 2026 19:02:53 +0200 [thread overview]
Message-ID: <2febb9ac-6b25-4037-8cdb-f8fe5734ec01@kernel.org> (raw)
In-Reply-To: <20260909115530.1924665-22-ardb+git@google.com>
On 9/9/26 13:55, Ard Biesheuvel wrote:
> From: Vincent Mailhol <mailhol@kernel.org>
>
> The Boot Loader Interface (BLI) [1] defines EFI variables that expose
> boot loader state to the running OS. LoaderInfo identifies the boot
> loader, while LoaderDevicePartUUID records the GPT partition UUID of
> the partition containing it.
>
> LoaderDevicePartUUID is used, for example, by systemd-gpt-auto-generator
> [2] to identify the disk the boot loader was launched from and
> automatically detect and mount partitions on it.
>
> GRUB [3] and systemd-boot [4] populate these variables, but when the
> kernel is started directly by EFI firmware, there is no conventional
> external boot loader to provide them. In that case, because the EFI stub
> performs the boot loader role, it should provide the variables itself.
>
> Use LoaderInfo as a sentinel: if it is already set by an earlier boot
> stage or cannot be set, bail out. Otherwise, populate the other BLI
> variables.
>
> Parse the loaded image device path, extract the GUID signature from its
> GPT HD() node and publish it under the Linux loader entry vendor GUID as
> the volatile LoaderDevicePartUUID EFI variable.
>
> Install the efi_bli_set_variables() hook in both the generic efi-stub.c
> path and the x86-specific x86-stub.c path.
>
> [1] The Boot Loader Interface
> Link: https://systemd.io/BOOT_LOADER_INTERFACE/
>
> [2] systemd-gpt-auto-generator
> Link: https://www.freedesktop.org/software/systemd/man/latest/systemd-gpt-auto-generator.html
>
> [3] GRUB -- §16.2 bli
> Link: https://www.gnu.org/software/grub/manual/grub/html_node/bli_005fmodule.html
>
> [4] systemd -- systemd-boot UEFI Boot Manager
> Link: https://github.com/systemd/systemd/blob/main/docs/BOOT.md?plain=1#L102
>
> Signed-off-by: Vincent Mailhol <mailhol@kernel.org>
> [ardb: - constify 'image' pointer parameter
> - pass efi_guid_t* to efi_snprintf()]
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
(...)
> diff --git a/drivers/firmware/efi/libstub/bli.c b/drivers/firmware/efi/libstub/bli.c
> new file mode 100644
> index 000000000000..b2407f63b743
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/bli.c
> @@ -0,0 +1,87 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <generated/utsrelease.h>
> +
> +#include <linux/efi.h>
> +#include <linux/errno.h>
<linux/errno.h> is not needed anymore following the changes in v3.
(Sorry, this is my mistake)
> +#include <linux/unaligned.h>
> +
> +#include "efistub.h"
(...)
Yours sincerely,
Vincent Mailhol
next prev parent reply other threads:[~2026-09-15 17:02 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 11:55 [PATCH v2 00/10] efi/libstub: Avoid UTF-16 conversion busywork Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 01/10] x86/boot: Drop pointless re-implementation of panic() Ard Biesheuvel
2026-09-09 19:14 ` Borislav Petkov
2026-09-09 20:43 ` Ard Biesheuvel
2026-09-10 13:12 ` Kiryl Shutsemau
2026-09-11 7:32 ` Ard Biesheuvel
2026-09-12 6:10 ` Borislav Petkov
2026-09-12 8:41 ` Ard Biesheuvel
2026-09-12 17:54 ` Borislav Petkov
2026-09-13 16:35 ` Ard Biesheuvel
2026-09-13 18:11 ` Borislav Petkov
2026-09-09 11:55 ` [PATCH v2 02/10] lib/ucs2_string: Drop arbitrary input size limit and associated WARN() Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 03/10] lib/ucs2_string: Suppress modinfo when __DISABLE_EXPORTS is set Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 04/10] lib/ucs2_string: Split out ucs2_as_utf8_l() taking a separate limit Ard Biesheuvel
2026-09-16 10:26 ` Vincent Mailhol
2026-09-09 11:55 ` [PATCH v2 05/10] efi/libstub: Use ucs2_string library for UTF-16 to UTF-8 conversion Ard Biesheuvel
2026-09-15 17:00 ` Vincent Mailhol
2026-09-09 11:55 ` [PATCH v2 06/10] efi/libstub: Avoid efi_puts() for compile time constant strings Ard Biesheuvel
2026-09-15 17:01 ` Vincent Mailhol
2026-09-09 11:55 ` [PATCH v2 07/10] efi/libstub: Output UTF-16 directly from vsnprintf() Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 08/10] efi/libstub: Add support for printing human readable GUIDs Ard Biesheuvel
2026-09-09 11:55 ` [PATCH v2 09/10] efi/libstub: Add efi_snprintf() to construct wide strings Ard Biesheuvel
2026-09-15 17:02 ` Vincent Mailhol
2026-09-09 11:55 ` [PATCH v2 10/10] efi/libstub: add initial Boot Loader Interface support Ard Biesheuvel
2026-09-15 17:02 ` Vincent Mailhol [this message]
2026-09-15 18:28 ` [PATCH v2 00/10] efi/libstub: Avoid UTF-16 conversion busywork Vincent Mailhol
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