[RFC PATCH 0/1] hw/arm: use -cpu max by default on sbsa-ref

[Leif Lindholm]

From: Leif Lindholm <Leif Lindholm quic_llindhol@quicinc.com>

We have mainly (well, as will become clear, in fact "exclusively") been using
sbsa-ref with the "max" CPU. But sbsa-ref was created with a default CPU of
Cortex-A57, which we have not updated along the way.

However, the "max" cpu has seen a bug where Linux boot fails around UEFI
ExitBootServices. Marcin Juszkiewicz has found the cause for that, but that
requires a patch to TF-A. (Has that been submitted upstream?)

Turns out that due to a change in upstream TF-A last year, all supported cpus
other than "max" fail to even boot UEFI fully, due to the top-level (TF-A)
Makefile defaulting to enabling the maximum ARM architectural version
(currently 8.6), in combination with not verifying all features at runtime
using the ID registers.

Since the *point* of sbsa-ref is to serve as a continuously evolving platform
tracking (with some obvious lag) the evolution of the ARM architecture and the
SystemReady specifications, I don't really want to restrict the enabled
feature set in TF-A to the Cortex-A57 one.

My preferred course of action would be to change the default cpu to max -
maybe even dropping support for other cpus. I would then step the version
field that was added to the DT. *But* this would break existing boots with
old TF-A that can currently boot Linux.

I did contemplate weaving this into the platform versioning, but truth is
I'm not convinced that would help ... and it would delay getting the
reworked memory map out.

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>
Cc: Shashi Mallela <shashi.mallela@linaro.org>
Cc: Radoslaw Biernacki <rad@semihalf.com>

Leif Lindholm (1):
  hw/arm: use -cpu max by default for sbsa-ref

 hw/arm/sbsa-ref.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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