Re: [PATCH 3/3] efi_loader: disk: add EFI_PARTITION_INFO_PROTOCOL support

[Heinrich Schuchardt]

Am 13. Juni 2025 10:57:38 MESZ schrieb Javier Martinez Canillas <javierm at redhat.com>:
>The UEFI 2.10 specification mentions that this protocol shall be installed
>along with EFI_BLOCK_IO_PROTOCOL. It provides cached partition information
>for MBR and GPT partition types.

U-Boot is targeting the EBBR specifcation which defines a subset of UEFI.

Which application needs this protocol?
Are you planning to add it to the EBBR specification?

Best regards 

Heinrich 



>
>This patch just implements support for GPT partition types. The legacy MBR
>partition types is only needed for backward compatibility and can be added
>as a follow-up if needed, to make it fully compliant with the EFI spec.
>
>Signed-off-by: Javier Martinez Canillas <javierm at redhat.com>
>---
>
> include/part_efi.h        | 20 ++++++++++++++++++++
> lib/efi_loader/efi_disk.c | 38 ++++++++++++++++++++++++++++++++++++--
> 2 files changed, 56 insertions(+), 2 deletions(-)
>
>diff --git a/include/part_efi.h b/include/part_efi.h
>index 59b7895b8a23..fb402df6f13e 100644
>--- a/include/part_efi.h
>+++ b/include/part_efi.h
>@@ -138,4 +138,24 @@ typedef struct _legacy_mbr {
> 	__le16 signature;
> } __packed legacy_mbr;
> 
>+#define EFI_PARTITION_INFO_PROTOCOL_GUID \
>+	EFI_GUID(0x8cf2f62c, 0xbc9b, 0x4821, 0x80, \
>+		 0x8d, 0xec, 0x9e, 0xc4, 0x21, 0xa1, 0xa0)
>+
>+#define EFI_PARTITION_INFO_PROTOCOL_REVISION 0x0001000
>+#define PARTITION_TYPE_OTHER 0x00
>+#define PARTITION_TYPE_MBR 0x01
>+#define PARTITION_TYPE_GPT 0x02
>+
>+struct efi_partition_info {
>+	u32 revision;
>+	u32 type;
>+	u8 system;
>+	u8 reserved[7];
>+	union {
>+		struct partition mbr;
>+		gpt_entry gpt;
>+	} info;
>+} __packed;
>+
> #endif	/* _DISK_PART_EFI_H */
>diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
>index 47b583cc5e12..ba41b77b9d1c 100644
>--- a/lib/efi_loader/efi_disk.c
>+++ b/lib/efi_loader/efi_disk.c
>@@ -26,6 +26,7 @@ struct efi_system_partition efi_system_partition = {
> 
> const efi_guid_t efi_block_io_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
> const efi_guid_t efi_system_partition_guid = PARTITION_SYSTEM_GUID;
>+const efi_guid_t efi_partition_info_guid = EFI_PARTITION_INFO_PROTOCOL_GUID;
> 
> /**
>  * struct efi_disk_obj - EFI disk object
>@@ -35,6 +36,7 @@ const efi_guid_t efi_system_partition_guid = PARTITION_SYSTEM_GUID;
>  * @media:	block I/O media information
>  * @dp:		device path to the block device
>  * @volume:	simple file system protocol of the partition
>+ * @info:	EFI partition info protocol interface
>  */
> struct efi_disk_obj {
> 	struct efi_object header;
>@@ -42,6 +44,7 @@ struct efi_disk_obj {
> 	struct efi_block_io_media media;
> 	struct efi_device_path *dp;
> 	struct efi_simple_file_system_protocol *volume;
>+	struct efi_partition_info info;
> };
> 
> /**
>@@ -426,6 +429,7 @@ static efi_status_t efi_disk_add_dev(
> 	/* Fill in object data */
> 	if (part_info) {
> 		struct efi_device_path *node = efi_dp_part_node(desc, part);
>+		struct efi_partition_info *info = &diskobj->info;
> 		struct efi_handler *handler;
> 		void *protocol_interface;
> 
>@@ -454,18 +458,47 @@ static efi_status_t efi_disk_add_dev(
> 			goto error;
> 		}
> 
>+		info->revision = EFI_PARTITION_INFO_PROTOCOL_REVISION;
>+
>+		switch (desc->part_type) {
>+		case PART_TYPE_EFI:
>+			info->type = PARTITION_TYPE_GPT;
>+			ret = part_get_gpt_pte(desc, part, &info->info.gpt);
>+			if (ret) {
>+				log_debug("get PTE for part %d failed %ld\n",
>+					  part, ret);
>+				goto error;
>+			}
>+
>+			break;
>+		case PART_TYPE_DOS:
>+			info->type = PARTITION_TYPE_MBR;
>+
>+			/* TODO: implement support for MBR partition types */
>+			log_debug("EFI_PARTITION_INFO_PROTOCOL doesn't support MBR\n");
>+
>+			break;
>+		default:
>+			info->type = PARTITION_TYPE_OTHER;
>+
>+			break;
>+		}
>+
> 		diskobj->dp = efi_dp_append_node(dp_parent, node);
> 		efi_free_pool(node);
> 		diskobj->media.last_block = part_info->size - 1;
>-		if (part_info->bootable & PART_EFI_SYSTEM_PARTITION)
>+		if (part_info->bootable & PART_EFI_SYSTEM_PARTITION) {
> 			esp_guid = &efi_system_partition_guid;
>+			info->system = 1;
>+		}
>+
> 	} else {
> 		diskobj->dp = efi_dp_from_part(desc, part);
> 		diskobj->media.last_block = desc->lba - 1;
> 	}
> 
> 	/*
>-	 * Install the device path and the block IO protocol.
>+	 * Install the device path, the block IO and partition info protocols.
> 	 *
> 	 * InstallMultipleProtocolInterfaces() checks if the device path is
> 	 * already installed on an other handle and returns EFI_ALREADY_STARTED
>@@ -476,6 +509,7 @@ static efi_status_t efi_disk_add_dev(
> 					&handle,
> 					&efi_guid_device_path, diskobj->dp,
> 					&efi_block_io_guid, &diskobj->ops,
>+					&efi_partition_info_guid, &diskobj->info,
> 					/*
> 					 * esp_guid must be last entry as it
> 					 * can be NULL. Its interface is NULL.