Re: Random reboots on ODROID-N2+

From: Neil Armstrong <narmstrong@baylibre.com>
To: Stefan Agner <stefan@agner.ch>, Robin Murphy <robin.murphy@arm.com>
Cc: Byron Stanoszek <gandalf@winds.org>,
	linux-amlogic@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	Jerome Brunet <jbrunet@baylibre.com>,
	Kevin Hilman <khilman@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Mike Rapoport <rppt@kernel.org>
Subject: Re: Random reboots on ODROID-N2+
Date: Mon, 26 Jul 2021 09:54:14 +0200	[thread overview]
Message-ID: <e0cd09ed-6c24-2bc6-c09a-0c0ccb7ae6c4@baylibre.com> (raw)
In-Reply-To: <50c6925775c207d0751e20fa9d45611a@agner.ch>

Hi,

On 23/07/2021 21:48, Stefan Agner wrote:
> On 2021-07-23 19:47, Robin Murphy wrote:
>> On 2021-07-23 17:14, Robin Murphy wrote:
>>> On 2021-07-23 16:56, Stefan Agner wrote:
> <snip>
>>>>>
>>>>> Booting with "efi=debug" should (among other things) print the memory
>>>>> map at boot if you want to double-check that that is the source of the
>>>>> mismatch. Our EFI code should be perfectly capable of setting the
>>>>> memblock flag if the region *is* described appropriately, see
>>>>> reserve_regions() in drivers/firmware/efi/efi-init.c.
>>>>
>>>> Booting 5.12.10 with "efi=debug" on U-Boot 2021.04 gave this:
>>>> [    0.000000] Machine model: Hardkernel ODROID-N2Plus
>>>> [    0.000000] efi: Getting UEFI parameters from /chosen in DT:
>>>> [    0.000000] efi: UEFI not found.
>>>> [    0.000000] OF: fdt: Reserved memory: failed to reserve memory for
>>>> node 'secmon@5000000': base 0x0000000005000000, size 3 MiB
>>>>
>>>> So it seems UEFI is not in the play here?
>>>
>>> Ah, OK, in that case I guess the question remains why does early_init_dt_reserve_memory_arch() think the region is already reserved? My instinctive assumption was an EFI memory map being present; seeing that U-Boot does indeed reflect DT reservations there *and* has had a likely-looking bug recently was then just overwhelmingly suggestive :)
>>
>> Actually, poking at U-Boot a bit more I find
>> meson_board_add_reserved_memory() - can you check /sys/firmware/fdt
>> and see if the region ends up being passed as a /memreserve/ as well
>> as a proper reserved-memory node?
>>
>> IIRC the semantics of /memreserve/ aren't really well-defined enough
>> to be suitable for the kind of things which require no-map, and my new
>> guess is that that's what ends up conflicting here.
> 
> Seems to be present in booth:

Indeed, in order so support any combination:
- upstream u-boot
- vendor u-boot
- upstream linux
- other OS

The secmon is in the upstream Linux DT, and upstream u-boot reads the secure memory regions
from the first stage bootloaders and adds them into the DT memreserve.

It worked fine since Linux 4.10-ish, until 5.10.

Neil

> 
> On v5.12.10
> # fdtdump /sys/firmware/fdt
> ...
> /memreserve/ 0x5000000 0x300000;
> ...
>     reserved-memory {
>         #address-cells = <0x00000002>;
>         #size-cells = <0x00000002>;
>         ranges;
>         secmon@5000000 {
>             reg = <0x00000000 0x05000000 0x00000000 0x00300000>;
>             no-map;
>             phandle = <0x00000068>;
>         };
>         linux,cma {
>             compatible = "shared-dma-pool";
>             reusable;
>             size = <0x00000000 0x10000000>;
>             alignment = <0x00000000 0x00400000>;
>             linux,cma-default;
>         };
>     };
> 
> --
> Stefan
> 

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