[PATCH v4 06/11] efi_loader: bootmgr: add booting from removable media
Heinrich Schuchardt
xypron.glpk at gmx.de
Sat Apr 2 08:12:36 CEST 2022
On 3/24/22 14:54, Masahisa Kojima wrote:
> From: AKASHI Takahiro <takahiro.akashi at linaro.org>
>
> Under the current implementation, booting from removable media using
> a architecture-specific default image name, say BOOTAA64.EFI, is
> supported only in distro_bootcmd script. See the commit 74522c898b35
> ("efi_loader: Add distro boot script for removable media").
>
> This is, however, half-baked implementation because
> 1) UEFI specification requires this feature to be implemented as part
> of Boot Manager's responsibility:
>
> 3 - Boot Manager
> 3.5.1 Boot via the Simple File Protocol
> When booting via the EFI_SIMPLE_FILE_SYSTEM_PROTOCOL, the FilePath will
> start with a device path that points to the device that implements the
> EFI_SIMPLE_FILE_SYSTEM_PROTOCOL or the EFI_BLOCK_IO_PROTOCOL. The next
> part of the FilePath may point to the file name, including
> subdirectories, which contain the bootable image. If the file name is
> a null device path, the file name must be generated from the rules
> defined below.
> ...
> 3.5.1.1 Removable Media Boot Behavior
> To generate a file name when none is present in the FilePath, the
> firmware must append a default file name in the form
> \EFI\BOOT\BOOT{machine type short-name}.EFI ...
>
> 2) So (1) entails the hehavior that the user's preference of boot media
> order should be determined by Boot#### and BootOrder variables.
At every boot you will have to delete autogenerated boot options and
create new ones according to the media which are present.
Your implementation does not offer any possibility to identify
autogenerated boot options.
On my laptop all autogenerated boot options use a VenMsg() device path
Boot0016* USB CD
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,86701296aa5a7848b66cd49dd3ba6a55)
Boot0017* USB FDD
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,6ff015a28830b543a8b8641009461e49)
Boot0018* NVMe0
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,001c199932d94c4eae9aa0b6e98eb8a400)
Boot0019* ATA HDD0
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f600)
Boot001A* USB HDD
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,33e821aaaf33bc4789bd419f88c50803)
Boot001B* PCI LAN
VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,78a84aaf2b2afc4ea79cf5cc8f3d3803)
while manual boot options use normal device paths
Boot0001* debian
HD(2,GPT,54e58b03-c1db-4c6b-afda-24340c3acda5,0x109000,0x32000)/File(\EFI\debian\shimx64.efi)
Boot0002* ubuntu
HD(2,GPT,54e58b03-c1db-4c6b-afda-24340c3acda5,0x109000,0x32000)/File(\EFI\ubuntu\shimx64.efi)
Please, provide a concept that can differentiate between autogenerated
and manually set boot options.
Best regards
Heinrich
>
> With this patch, the semantics mentioned above is fully implemented.
> For example, if you want to boot the system from USB and SCSI in this
> order,
> * define Boot0001 which contains only a device path to the USB device
> (without any file path/name)
> * define Boot0002 which contains only a device path to the SCSI device,
> and
> * set BootOrder to Boot0001:Boot0002
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
> ---
> Changes from original version:
> - create new include file "efi_default_filename.h" to
> avoid conflict with config_distro_bootcmd.h
> - modify the target pointer of efi_free_pool(), expand_media_path() should
> only free the pointer allocated by efi_dp_from_file() function.
>
> include/config_distro_bootcmd.h | 14 +--------
> include/efi_default_filename.h | 26 +++++++++++++++++
> lib/efi_loader/efi_bootmgr.c | 50 ++++++++++++++++++++++++++++++++-
> 3 files changed, 76 insertions(+), 14 deletions(-)
> create mode 100644 include/efi_default_filename.h
>
> diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
> index 2f90929178..ef2c9f330e 100644
> --- a/include/config_distro_bootcmd.h
> +++ b/include/config_distro_bootcmd.h
> @@ -91,19 +91,7 @@
> #endif
>
> #ifdef CONFIG_EFI_LOADER
> -#if defined(CONFIG_ARM64)
> -#define BOOTEFI_NAME "bootaa64.efi"
> -#elif defined(CONFIG_ARM)
> -#define BOOTEFI_NAME "bootarm.efi"
> -#elif defined(CONFIG_X86_RUN_32BIT)
> -#define BOOTEFI_NAME "bootia32.efi"
> -#elif defined(CONFIG_X86_RUN_64BIT)
> -#define BOOTEFI_NAME "bootx64.efi"
> -#elif defined(CONFIG_ARCH_RV32I)
> -#define BOOTEFI_NAME "bootriscv32.efi"
> -#elif defined(CONFIG_ARCH_RV64I)
> -#define BOOTEFI_NAME "bootriscv64.efi"
> -#endif
> +#include <efi_default_filename.h>
> #endif
>
> #ifdef BOOTEFI_NAME
> diff --git a/include/efi_default_filename.h b/include/efi_default_filename.h
> new file mode 100644
> index 0000000000..de030d2692
> --- /dev/null
> +++ b/include/efi_default_filename.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Default boot file name when none is present in the FilePath.
> + *
> + * Copyright (c) 2022, Linaro Limited
> + */
> +#ifndef _EFI_DEFAULT_FILENAME_H
> +#define _EFI_DEFAULT_FILENAME_H
> +
> +#if defined(CONFIG_ARM64)
> +#define BOOTEFI_NAME "BOOTAA64.EFI"
> +#elif defined(CONFIG_ARM)
> +#define BOOTEFI_NAME "BOOTARM.EFI"
> +#elif defined(CONFIG_X86_64)
> +#define BOOTEFI_NAME "BOOTX64.EFI"
> +#elif defined(CONFIG_X86)
> +#define BOOTEFI_NAME "BOOTIA32.EFI"
> +#elif defined(CONFIG_ARCH_RV32I)
> +#define BOOTEFI_NAME "BOOTRISCV32.EFI"
> +#elif defined(CONFIG_ARCH_RV64I)
> +#define BOOTEFI_NAME "BOOTRISCV64.EFI"
> +#else
> +#error Unsupported UEFI architecture
> +#endif
> +
> +#endif
> diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> index 8c04ecbdc8..22a4302aac 100644
> --- a/lib/efi_loader/efi_bootmgr.c
> +++ b/lib/efi_loader/efi_bootmgr.c
> @@ -11,6 +11,7 @@
> #include <charset.h>
> #include <log.h>
> #include <malloc.h>
> +#include <efi_default_filename.h>
> #include <efi_loader.h>
> #include <efi_variable.h>
> #include <asm/unaligned.h>
> @@ -30,6 +31,50 @@ static const struct efi_runtime_services *rs;
> * should do normal or recovery boot.
> */
>
> +/**
> + * expand_media_path() - expand a device path for default file name
> + * @device_path: device path to check against
> + *
> + * If @device_path is a media or disk partition which houses a file
> + * system, this function returns a full device path which contains
> + * an architecture-specific default file name for removable media.
> + *
> + * Return: a newly allocated device path
> + */
> +static
> +struct efi_device_path *expand_media_path(struct efi_device_path *device_path)
> +{
> + struct efi_device_path *dp, *full_path;
> + efi_handle_t handle;
> + efi_status_t ret;
> +
> + if (!device_path)
> + return NULL;
> +
> + /*
> + * If device_path is a (removable) media or partition which provides
> + * simple file system protocol, append a default file name to support
> + * booting from removable media.
> + */
> + dp = device_path;
> + ret = efi_locate_device_path(&efi_simple_file_system_protocol_guid,
> + &dp, &handle);
> + if (ret == EFI_SUCCESS) {
> + if (dp->type == DEVICE_PATH_TYPE_END) {
> + dp = efi_dp_from_file(NULL, 0,
> + "/EFI/BOOT/" BOOTEFI_NAME);
> + full_path = efi_dp_append(device_path, dp);
> + efi_free_pool(dp);
> + } else {
> + full_path = efi_dp_dup(device_path);
> + }
> + } else {
> + full_path = efi_dp_dup(device_path);
> + }
> +
> + return full_path;
> +}
> +
> /**
> * try_load_entry() - try to load image for boot option
> *
> @@ -68,13 +113,16 @@ static efi_status_t try_load_entry(u16 n, efi_handle_t *handle,
> }
>
> if (lo.attributes & LOAD_OPTION_ACTIVE) {
> + struct efi_device_path *file_path;
> u32 attributes;
>
> log_debug("%s: trying to load \"%ls\" from %pD\n",
> __func__, lo.label, lo.file_path);
>
> - ret = EFI_CALL(efi_load_image(true, efi_root, lo.file_path,
> + file_path = expand_media_path(lo.file_path);
> + ret = EFI_CALL(efi_load_image(true, efi_root, file_path,
> NULL, 0, handle));
> + efi_free_pool(file_path);
> if (ret != EFI_SUCCESS) {
> log_warning("Loading %ls '%ls' failed\n",
> varname, lo.label);
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