[PATCH v2 2/2] efi_loader: identify EFI system partition

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Heinrich,

On Mon, Apr 06, 2020 at 02:31:35PM +0900, AKASHI Takahiro wrote:
> On Mon, Apr 06, 2020 at 07:12:56AM +0200, Heinrich Schuchardt wrote:
> > On 4/6/20 6:21 AM, AKASHI Takahiro wrote:
> > > Heinrich,
> > >
> > > On Sun, Apr 05, 2020 at 11:28:18AM +0200, Heinrich Schuchardt wrote:
> > >> For capsule updates we need to identify the EFI system partition.
> > >
> > > Right, but
> > >
> > >> Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> > >> ---
> > >> v2:
> > >> 	no change
> > >> ---
> > >>  include/efi_loader.h      |  7 +++++++
> > >>  lib/efi_loader/efi_disk.c | 20 ++++++++++++++++++++
> > >>  2 files changed, 27 insertions(+)
> > >>
> > >> diff --git a/include/efi_loader.h b/include/efi_loader.h
> > >> index 3f2792892f..4a45033476 100644
> > >> --- a/include/efi_loader.h
> > >> +++ b/include/efi_loader.h
> > >> @@ -45,6 +45,13 @@ static inline void *guidcpy(void *dst, const void *src)
> > >>  /* Root node */
> > >>  extern efi_handle_t efi_root;
> > >>
> > >> +/* EFI system partition */
> > >> +extern struct efi_system_partition {
> > >> +	enum if_type if_type;
> > >> +	int devnum;
> > >> +	u8 part;
> > >> +} efi_system_partition;
> > >> +
> > >>  int __efi_entry_check(void);
> > >>  int __efi_exit_check(void);
> > >>  const char *__efi_nesting(void);
> > >> diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
> > >> index fc0682bc48..2f752a5e99 100644
> > >> --- a/lib/efi_loader/efi_disk.c
> > >> +++ b/lib/efi_loader/efi_disk.c
> > >> @@ -13,6 +13,8 @@
> > >>  #include <part.h>
> > >>  #include <malloc.h>
> > >>
> > >> +struct efi_system_partition efi_system_partition;
> > >> +
> > >>  const efi_guid_t efi_block_io_guid = EFI_BLOCK_IO_PROTOCOL_GUID;
> > >>
> > >>  /**
> > >> @@ -372,6 +374,24 @@ static efi_status_t efi_disk_add_dev(
> > >>  	diskobj->ops.media = &diskobj->media;
> > >>  	if (disk)
> > >>  		*disk = diskobj;
> > >> +
> > >> +	/* Store first EFI system partition */
> > >
> > > I don't think that the policy, first comes first serves as system
> > > partition, is a right decision as
> > > - the order of device probe on U-Boot is indeterministic, and
> > 
> > Indeterministic would mean that on two runs with the same media provided
> > you will get different results. I cannot see any source for such
> > randomness in the U-Boot code. In dm_init_and_scan() the device tree is
> > scanned and drivers and bound in the sequence of occurrence in the
> > device tree.
> > 
> > > - there can be several partitions that hold a system partition bit.
> > >   You may have OS installed on eMMC, but also may have bootable DVD
> > >   on the system.
> > 
> > This is a similar logic like finding the relevant boot.scr script to run.
> > 
> > What would be the alternative?
> 
> I think that most UEFI systems have ability for user to specify
> "boot order."

Any comment?
The discussion and your patch will have some impact on
my efi capsule patch.

-Takahiro Akashi

> -Takahiro Akashi
> > 
> > Definition via Kconfig would mean that a Linux distribution like Debian
> > would have to provide a separate U-Boot build for each boot medium that
> > a user might possibly use (eMMC, SD-card, USB, NVME, SCSI).
> > 
> > Best regards
> > 
> > Heinrich
> > 
> > >
> > > -Takahiro Akashi
> > >
> > >> +	if (part && !efi_system_partition.if_type) {
> > >> +		int r;
> > >> +		disk_partition_t info;
> > >> +
> > >> +		r = part_get_info(desc, part, &info);
> > >> +		if (r)
> > >> +			return EFI_DEVICE_ERROR;
> > >> +		if (info.bootable & PART_EFI_SYSTEM_PARTITION) {
> > >> +			efi_system_partition.if_type = desc->if_type;
> > >> +			efi_system_partition.devnum = desc->devnum;
> > >> +			efi_system_partition.part = part;
> > >> +			EFI_PRINT("EFI system partition: %s %d:%d\n",
> > >> +				  blk_get_if_type_name(desc->if_type),
> > >> +				  desc->devnum, part);
> > >> +		}
> > >> +	}
> > >>  	return EFI_SUCCESS;
> > >>  }
> > >>
> > >> --
> > >> 2.25.1
> > >>
> >