On 11/12/20 11:55, Qais Yousef wrote:

On 11/12/20 10:24, Will Deacon wrote:

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On Wed, Nov 11, 2020 at 04:27:00PM +0000, Qais Yousef wrote:

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On 11/09/20 13:52, Will Deacon wrote:

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On Fri, Nov 06, 2020 at 02:48:35PM +0000, Qais Yousef wrote:

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On 11/06/20 13:00, Will Deacon wrote:

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On Fri, Nov 06, 2020 at 12:54:25PM +0000, Qais Yousef wrote:

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FWIW I have my v3 over here in case it's of any help. It solves the problem of
HWCAP discovery when late AArch32 CPU is booted by populating boot_cpu_date
with 32bit features then.

	git clone https://git.gitlab.arm.com/linux-arm/linux-qy.git -b asym-aarch32-upstream-v3 origin/asym-aarch32-upstream-v3

Cheers, I've done something similar. I was hoping to post it today, but I've
been side-tracked with bug fixing this morning. The main headache I ended up
with was allowing late-onlining of 64-bit-only CPUs if all the boot CPUs
are 32-bit capable. What do you do in that case?

Do you mean if CPUs 0-3 were 32bit capable and we boot with maxcpus=4 then
attempt to bring the remaining 64bit-only cpus online later?

Right. I think we will refuse to online them. I'll post my attempt at
handling that shortly.

Sorry for the delayed response.

You're right, I tried that and they refuse to come online. We missed that tbh.

Haven't thought what we should do yet. I tried your v2 and it failed similarly.

Hmm, it shouldn't do. Please could you provide the log? My hunch is that you
are blatting 32-bit EL1 support as well, and we can't handle a mismatch for
that with a late CPU. Do you know if the CPUs being integrated into these
broken designs have a mismatch at EL1 as well?

Hmm my test could have been invalid then. We shouldn't have mismatch at EL1,
for ease of testing I used a hacked up patch to fake asymmetry on Juno. Testing
on FVP now, it takes time to boot up though..

Let me re-run this and get you the log from proper environment. Assuming it
still fails.

Still fails the same on FVP. dmesg attached. There's a splat shortly after
attempting to online CPU 4.

	# cat /sys/devices/system/cpu/online
	0-3
	# cat /sys/devices/system/cpu/aarch32_el0
	0-3

Now while writing this I just realized I tell the FVP to disable aarch32
support at EL0. So this might still make the kernel thinks there's AArch32
support at EL1 - which seems is what makes your series get confused?

Anyway. No real hardware to test on and not sure if I can tell the FVP to
disable AArch32 support at EL1.

/me goes and dig

Thanks

--
Qais Yousef