On Tue, 2021-03-09 at 19:38 +0100, Heinrich Schuchardt wrote:

On 09.03.21 18:31, Kumar Sankaran wrote:

Hi Heinrich,

Agree, I think using the term UEFI is confusing since it is a
specification. It should instead be called EDK II or Tianocore.
Will
make the change.

The reason for having U-Boot and EDK II (UEFI) was to specify which
boot-loader would be started by OpenSBI. Right now, everyone I
believe
is using U-boot as the default bootloader. I was suggesting we drop
U-boot completely and switch to using EDK II as the standard boot-
loader
and use the UEFI entry point to launch the OS.

Adding EDK-II support for platforms usually takes more effort than U-
Boot. I think we should keep U-Boot/EDK-II for the base and may choose
only EDK-II for server extension.

Hello Kumar,

OpenSBI can collaborate both with both EDK II and U-Boot. For the
Linux
platform this should not make a difference as long as the UEFI
firmware
implementation and the SBI implementation are compliant.

The relevant question is which part of UEFI has to be implemented.
ARM
has driven the definition of two profiles:

EBBR for embedded boards
https://github.com/ARM-software/ebbr
and

SBBR for servers

https://static.docs.arm.com/den0044/12/Server_Base_Boot_Requirements-1.2.pdf
.

U-Boot only targets the EBBR specification while EDK II is the UEFI
reference implementation and complies to the SBBR.

My idea is that the envisioned RISC-V Linux platform specification
should either refer to the EBBR and SBBR or define its own subset of
UEFI that has to be implemented by the firmware. It should not
require a
specific software implementation.

I would prefer if the base requirement were to have an UEFI
implementation that matches the EBBR

That is still the intention for base Linux platform specification.
That's why, I had sent the patch for RISC-V support to EBBR.

and for servers to comply with the
SBBR instead of defining new profiles.

I am not sure if that is feasible because of SBBR is a completely ARM
specification and comes under Arm Non-Confidential Document Licence
(“Licence”). Legal guys may have to weigh on this.

ARM is open to add RISC-V requirements to the EBBR spec. Atish joined
some of the EBBR meetings.

Unfortunately, I couldn't attend any recent meetings due to the
conflict with platform meeting. That shouldn't be an once the DST
starts.

Best regards

Heinrich

 

Regards

Kumar

*From:* Heinrich Schuchardt <xypron.glpk@...
<mailto:xypron.glpk@...>>
*Sent:* Tuesday, March 9, 2021 3:45 AM
*To:* Kumar Sankaran <ksankaran@...
<mailto:ksankaran@...>>
*Subject:* Re: [RISC-V] [tech-unixplatformspec] Platform Spec
Chapters
and Owners

 

Item 5.2 Boot-Loader has entries U-Boot and UEFI. This is
confusing.
Both U-Boot and EDK II implement the UEFI specification. The Linux
kernel has a UEFI and a non-UEFI entry point which can be invoked
by
OpenSBI or U-Boot. I think UEFI should be the default way to start
operating systems.

So maybe:

5.2 Boot-Loader

  * UEFI
  * non-UEFI Linux invocation

Best regards

Heinrich

--
Regards,
Atish