[PATCH 0/7] Add support for CONFIG_API on RISC-V

[Heinrich Schuchardt]

On 4/24/20 10:52 PM, Tom Rini wrote:
> On Fri, Apr 24, 2020 at 05:46:43PM -0300, Mitchell Horne wrote:
>> On Fri, Apr 24, 2020 at 1:52 PM Tom Rini <trini at konsulko.com> wrote:
>>>
>>> On Mon, Apr 20, 2020 at 06:34:11PM -0400, mhorne at FreeBSD.org wrote:
>>>
>>>> From: Mitchell Horne <mhorne at FreeBSD.org>
>>>>
>>>> FreeBSD makes use of u-boot's CONFIG_API to provide a version of its
>>>> standard bootloader for embedded architectures. This series adds the
>>>> necessary support for the RISC-V architecture, along with some small
>>>> fixes to the API demo program for 64-bit systems.
>>>
>>> Adding in the RISC-V maintainer and EFI maintainer.  I thought the
>>> intention was for OSes to use the EFI loader here, even for "embedded" ?
>>> Thanks!
>>>
>>
>> Hi Tom,
>>
>> You are right, EFI is preferred. FreeBSD's loader has two
>> implementations on arm: one that is an EFI application, and one based
>> on this u-boot API (known as "ubldr"). ubldr precedes the EFI
>> implementation by a few years.
>>
>> For RISC-V my intention is also to implement both versions, and ubldr
>> was simpler on FreeBSD's side, so I chose to do that first. Do you
>> think this series is still worth pursuing if u-boot is going the way
>> of EFI?
>
> In my mind at least, the EFI interface is preferred as it's a defined
> external standard interface.  If the architecture maintainers want to
> support both the U-Boot API and EFI on RISC-V, I don't object.  But one
> of the intentions is to have there be less work for OS folks to have to
> do for example.  So that you found this a good first step for your use
> case means perhaps we need to continue to have the U-Boot API method be
> around (not that we had planned any sort of removal).  Thanks!
>

Hello Mitchell,

let me just give me an overview of where we currently are with UEFI
support for RISC-V:

U-Boot supports UEFI to the point that we can start GRUB as EFI binary.

In Linux the UEFI support for RISC-V is being set up, cf.
https://lkml.org/lkml/2020/4/20/1800

In EDK2 RISC-V support is under active development
(https://edk2.groups.io/g/devel/search?q=RISC-V). In EDK2's staging
repository (https://github.com/tianocore/edk2-staging.git) you can find
a branch RISC-V-V2-CI-log-all-archs.

One challenge is the transfer of the HART id which is used for booting.
In U-Boot this has been addressed by the patch 5370478d1c7a ("riscv: Add
boot hartid to device tree").

@Atish:
Is there a corresponding patch for EDK2?

Best regards

Heinrich