Kojima-san,
On Tue, Aug 25, 2020 at 21:34:01 +0900, Masahisa Kojima wrote:
On Wed, 12 Aug 2020 at 19:41, Leif Lindholm via Asa-dev asa-dev@op-lists.linaro.org wrote:
Hi all,
We've started looking at the TF-A qemu_sbsa port a bit, and found some things that were carried over from the mach-virt port for no good reason:
Looking at plat/qemu/qemu_sbsa/platform.mk:
- lib/cpus/aarch64/aem_generic.S is for fast models/foundation model.
- although we may want to add a "generic armv8 cpu" to TF-A at some point, to reduce synchronization needs when bumping the cpu used by sbsa-ref in upstream QEMU.
For now, do we need to remove lib/cpus/aarch64/aem_generic.S and lib/cpus/aarch64/cortex_a57.S from sbsa-qemu?
It makes sense to remove aem_generic.S. It is not a CPU QEMU can emulate, it is ARM's Fast Models/Foundation Model. (It probably shouldn't even be in the basic "qemu" platform.)
We must keep A57 for now, since that is the only supported CPU for this platform in QEMU. My intent for sbsa-ref was to always track the latest cpu supported in upstream QEMU. Today, that would not mean a57, but either a72 or "max". We may need to "bump" this in QEMU at some point. It would make sense to keep support in TF-A for some time after changing QEMU, but remove it eventually.
- lib/cpus/aarch64/cortex_a53.S is not supported by sbsa-ref, nor does the A53 support enough physical address bits to be able to control this platform.
I'm not familiar with this item, is this a matter of QEMU side?
Yes. The qemu system memory map creates a larger physical address space than the A53 model can access.
- drivers/io/io_semihosting.c, lib/semihosting/semihosting.c, and lib/semihosting/${ARCH}/semihosting_call.S are not actually used. But there *are* some other bits of qemu/common code which needs to be cinditionalized-out if these files aren't included.
We are not using semi-hosting, I will try to remove these files from the build target.
Thank you.
- plat/common/plat_psci_common.c
- all of the ${ARCH} stanzas should just be 'aarch64', this platform cannot be booted in aarch32.
I will fix this.
Thank you.
- plat/common/plat_psci_common.c isn't usefully hooked up to anything at the moment, but we can fix that when we get to actually implementing useful PSCI. That file may simply not belong in 'common'.
I'm still checking the contents of plat/common/plat_psci_common.c, most of the functions are optional.
You can ignore this point: Graeme has sent out patches to qemu to enable TF-A to handle PSCI via a trivial modelled power controller. Once that is acked upstream, I'm sure he will upstream the TF-A driver for this device. (https://lists.gnu.org/archive/html/qemu-devel/2020-08/msg04795.html)
Best Regards,
Leif
Regards, Masahisa
/ Leif
)
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