On Sat, May 10, 2025 at 03:42:07PM +0200, Simon Glass wrote: > Accept a bloblist and control devicetree from a previous phase in > registers 0 to 3, as documented in the Firmware Handoff > specification[1]. > > Note that there is currently a weak function called save_boot_params() > which happens to save the same registers as are needed for this > protocol. But it seems better to implement this feature as a first-class > citizen, if for no other reason than that many boards have their own > version of save_boot_params() which may not happen to save the required > registers. A weak function is not a good basis for an API. > > [1] https://firmwarehandoff.github.io/firmware_handoff/main/index.html > > Signed-off-by: Simon Glass <s...@chromium.org> > --- > While some efforts were made to encourage Intel to adopt this > specification, this has not yet been successful. However I do intend to > use my proposed x86 handoff in U-Boot, once this series is in. > > Changes in v4: > - Update commit message to indicate this can only be for ARM at present > - Update commit message to mention why save_boot_params() is not used > > Changes in v3: > - Add support for aarch64 also > - Update registers to match the Firmware Handoff protocol > > Changes in v2: > - Use three registers instead of two for the entry > > arch/arm/cpu/armv7/start.S | 10 +++++++++- > arch/arm/cpu/armv8/start.S | 12 ++++++++++++ > arch/arm/lib/crt0.S | 6 ++++++ > arch/arm/lib/crt0_64.S | 6 ++++++ > 4 files changed, 33 insertions(+), 1 deletion(-)
This is what makes me think you aren't actually working on my feedback
about taking what we have in-tree, now, rather than just forward porting
your old series and deleting the current code.
We have save_boot_params doing exactly what it should today, including
saving off a standard passage and making what was saved available later,
in an intentional fashion. If, hypothetically, Pi needs to override
save_boot_param because a future new-firmware-blob does standard passage
but at run time we want to support both, that's a good thing.
With commit ea3348ebc215 ('Merge patch series "Handoff bloblist from
previous boot stage"') we already implement the specification in [1]. It
is not a "which happens to". It is intentional.
I guess the overall challenge here is that you want to do things which
are a superset of the firmware handoff spec itself?
--
Tom
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