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: Thu, 5 Dec 2019 15:48:54 +0100	[thread overview]
Message-ID: <40a0e25a-9752-7bca-da1c-51135582907d@forissier.org> (raw)
In-Reply-To: <ee5970f9-a9c3-619e-7674-8a98ffcaeec1@arm.com>

On 12/5/19 1:04 PM, Vincenzo Frascino wrote:
> Hi Jerome,
> 
> On 04/12/2019 14:03, Jerome Forissier wrote:
> [...]
>> 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
>>
> 
> Thank you for the instructions, I managed to successfully boot the latest
> mainline tree on the Hikey960. Full log in attachment.
> And even the poweroff sequence looks fine to me.

Nice.

> Could you please try to follow the following steps and verify that it works for
> you as well?
> 
> 1. Download op-tee version 3.7.0.
> 2. Enter the linux directory and add the remote
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> 3. Rebase the 3.7.0 branch kernel of linux master.
> 4. Build and Flash op-tee.
> 
> It should boot and have no issues on init.

[Unfortunately, it doesn't work for me. The board still hangs (or
rather, loops) on /init. I'm puzzled at this point... What could be
wrong with my setup? Do we have different board revisions maybe?

...]

Now that's embarrassing :-/ I decided to re-build everything once again,
but *without ccache* this time. Guess what? Kernel v5.4 boots fine :-O
and master too.

I used to trust ccache blindly, until I discovered a bug which has
caused me some trouble for quite some time [1]. After upgrading I
thought all would be good again, but apparently not... That is quite
annoying! :-/

Would you recommend against using ccache for kernel development?

Anyway, thank you guys for your valuable help. I feel ashamed for
wasting your time troubleshooting a non-bug... but at least it wasn't in
vain.

[1] https://github.com/ccache/ccache/issues/136

> What I noticed is that the optee
> provided kernel is not a 5.1 but a 5.1 plus some patches.

True, but nothing really important. A vanilla kernel is supposed to work
fine including most of the OP-TEE stuff (except for some very specific
"secure data path" code which depends on the presence of a special ION
heap).

Thanks,
-- 
Jerome

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