On 8/13/21 2:36 AM, Heinrich Schuchardt wrote:
On 8/12/21 11:49 PM, Simon Glass wrote:
+Heinrich Schuchardt too
On Thu, 12 Aug 2021 at 08:35, Christian Melki
<christian.me...@t2data.com> wrote:
I was hoping that U-boot would detect BLOCK_IO devices provided by UEFI
automatically. But I can't see anything attached under lsblk or find
some other information about this.
For example, Barebox works just fine on both Virtualbox and real
hardware in this regard.
Barebox does not have an emmc driver for the real hardware but
piggybacks off the UEFI protocol for this.
Hello Christian,
U-Boot can be used in two scenarios:
1) U-Boot is the firmware providing the UEFI API
2) U-Boot is running as an application consuming the UEFI API.
Barebox only supports scenario 2).
Ok.
I'm sure that the idea with this U-boot driver is something like that,
but would appreciate some hints on how to use it.
efi_driver/efi_block_device.c is used in scenario 1).
When a UEFI payload like iPXE provides an EFI_BLOCK_IO_PROTOCOL on a
handle and calls ConnectController() U-Boot will install the
EFI_SIMPLE_FILE_PROTOCOL for each partition on the block device.
You can find a detailed description of this use case in:
* https://u-boot.readthedocs.io/en/latest/develop/uefi/iscsi.html
* https://archive.fosdem.org/2020/schedule/event/firmware_duwu/
I read the fosdem presentation, but apparently did not understand it
correctly, as I thought it could be used for presenting the UEFI block
IO protocol.
Ie, standard usage. UEFI boots of a drive, posts some handles(?) to a
block device and U-boot picks it up, not knowing more about the
abstracted hardware.
Here you seem be referring to scenario 2).
For scenario 2) support for UEFI block devices has not been implemented,
yet. As operating systems like Linux, BSD, Windows all can be booted via
UEFI there has not been any use case driving further development of this
scenario.
Please, describe what you want to do with U-Boot.
I have an x86 board (DFI GHF51, AMD Ryzen R1000) with an ACPI presented
eMMC. AMDI0040. U-boot does not seem to recognize this device (Linux
works fine.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mmc/host/sdhci-acpi.c).
So I thought the UEFI block IO protocol could come in handy as a generic
abstraction. The device works fine under Barebox with this mechanism. So
without a native or an UEFI block IO driver I have no disc access in U-boot.
I know that UEFI can boot a EFI-stubbed kernel directly. But I am more
comfortable with the U-boot "ecosystem" than UEFI, also it is easier to
merge more platforms under the same (existing) boot
mechanism/behavior/environment using U-boot as an intermediate than just
UEFI (older ARM/PPC etc).
So definitely an use-case for me.
Thanks in advance,
Christian
Best regards
Heinrich
