Re: Kernel v5.2+ on HiKey960?

From: Jerome Forissier <jerome@forissier.org>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: Kernel v5.2+ on HiKey960?
Date: Wed, 4 Dec 2019 15:03:55 +0100	[thread overview]
Message-ID: <63c92257-1915-7374-64de-0e73804167e0@forissier.org> (raw)
In-Reply-To: <a24f817e-86dc-ae32-417d-08eadc96d0eb@arm.com>

On 12/4/19 1:55 PM, Vincenzo Frascino wrote:
> On 12/4/19 10:18 AM, Catalin Marinas wrote:
>>> 1. "arm64: vdso: Substitute gettimeofday() with C implementation"
>> Commit 28b1a824a4f4, merged in 5.3
>>
>>> 2. "arm64: vdso: Explicitly add build-id option"
>> Commit 7a0a93c51799, merged in 5.2
>>
>>> 3. "arm64: arch_timer: Ensure counter register reads occur with seqlock
>>>     held"
>> Commit 75a19a0202db, merged in 5.2.
>>
>>> 4. "arm64: vdso: Remove stale files from old assembly implementation"
>> Commit 37a5076098c1, merged in 5.4.
>>
>> The above is a pretty random set of reverts that doesn't really help
>> pinpoint the issue.
>>
>> Since 5.2 was the first kernel where the regression was noticed, could
>> you try reverting commit 75a19a0202db in 5.2 and try that specific
>> kernel version? If this doesn't solve the issue, it may be simpler to
>> bisect only between 5.1 and 5.2 rather than across multiple kernel
>> versions.
> 
> I agree with Catalin here. The unified vDSO change is a 5.3+ change, should not
> impact what you are seeing in 5.2.
> 
> Could you please as well provide some guidelines to reproduce your scenario
> exactly? This would help in the debugging.
> 

Do you have a HiKey960 board at your disposal? Well, you can build the
whole stuff I'm using by following the OP-TEE build instructions [1],
just use 'hikey960' for ${TARGET} in the description.

The scenario is simple: build, flash, power-cycle the board. That's it.
Default version boots fine (it's based on a v5.1 kernel), but checkout
Linux v5.4 instead and the login prompt never shows up on the UART console.

Note, if you just want to build the kernel Image you may simply run
"make linux" instead of "make".

[1]
https://optee.readthedocs.io/en/latest/building/gits/build.html#get-and-build-the-solution

Thanks,
-- 
Jerome

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