efi_loader: bootmgr: add booting from removable media
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.
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
To avoid build error for sandbox, default file name "BOOTSANDBOX.efi"
is defined even if it is out of scope of UEFI specification.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>
On sandbox use binary name corresponding to host architecture.
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/include/efi_default_filename.h b/include/efi_default_filename.h
new file mode 100644
index 0000000..13b9de8
--- /dev/null
+++ b/include/efi_default_filename.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * When a boot option does not provide a file path the EFI file to be
+ * booted is \EFI\BOOT\$(BOOTEFI_NAME).EFI. The architecture specific
+ * file name is defined in this include.
+ *
+ * Copyright (c) 2022, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#ifndef _EFI_DEFAULT_FILENAME_H
+#define _EFI_DEFAULT_FILENAME_H
+
+#include <host_arch.h>
+
+#undef BOOTEFI_NAME
+
+#if HOST_ARCH == HOST_ARCH_X86_64
+#define BOOTEFI_NAME "BOOTX64.EFI"
+#endif
+
+#if HOST_ARCH == HOST_ARCH_X86
+#define BOOTEFI_NAME "BOOTIA32.EFI"
+#endif
+
+#if HOST_ARCH == HOST_ARCH_AARCH64
+#define BOOTEFI_NAME "BOOTAA64.EFI"
+#endif
+
+#if HOST_ARCH == HOST_ARCH_ARM
+#define BOOTEFI_NAME "BOOTARM.EFI"
+#endif
+
+#if HOST_ARCH == HOST_ARCH_RISCV32
+#define BOOTEFI_NAME "BOOTRISCV32.EFI"
+#endif
+
+#if HOST_ARCH == HOST_ARCH_RISCV64
+#define BOOTEFI_NAME "BOOTRISCV64.EFI"
+#endif
+
+#ifndef BOOTEFI_NAME
+#error Unsupported UEFI architecture
+#endif
+
+#endif
diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
index 52bea4d..631a25d 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>
@@ -31,6 +32,51 @@
*/
/**
+ * 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_CALL(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
*
* Attempt to load load-option number 'n', returning device_path and file_path
@@ -64,13 +110,16 @@
}
if (lo.attributes & LOAD_OPTION_ACTIVE) {
+ struct efi_device_path *file_path;
u32 attributes;
log_debug("trying to load \"%ls\" from %pD\n", 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);