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Date:   Mon, 5 Sep 2022 13:18:32 +0200
From:   Maxime Ripard <maxime@cerno.tech>
To:     "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
        Olof Johansson <olof@lixom.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Daniel Vetter <daniel.vetter@intel.com>,
        David Airlie <airlied@linux.ie>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Roman Gushchin <roman.gushchin@linux.dev>
Cc:     Martin Roukala <martin.roukala@mupuf.org>, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: RaspberryPi4 Panic in net_ns_init()
Message-ID: <20220905111832.73nqtlzpiuwpj7lx@houat>
References: <20220831144205.iirdun6bf3j5v6q4@houat>
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On Wed, Aug 31, 2022 at 04:42:05PM +0200, Maxime Ripard wrote:
> Sorry for the fairly broad list of recipients, I'm not entirely sure
> where the issue lies exactly, and it seems like multiple areas are
> involved.
>=20
> Martin reported me an issue discovered with the VC4 DRM driver that
> would prevent the RaspberryPi4 from booting entirely. At boot, and
> apparently before the console initialization, the board would just die.
>=20
> It first appeared when both DYNAMIC_DEBUG and DRM_VC4 were built-in. We
> started to look into what configuration would trigger it.
>=20
> It looks like a good reproducer is:
>=20
> ARCH=3Darm64 CROSS_COMPILE=3Daarch64-linux-gnu- make -j18 defconfig mod2y=
esconfig
> ./scripts/config -e CONFIG_DYNAMIC_DEBUG
> ARCH=3Darm64 CROSS_COMPILE=3Daarch64-linux-gnu- make -j18 olddefconfig

Interestingly, this was making the kernel Image cross the 64MB boundary.
I've compiled the same configuration but with -Os, and then tried to
boot the failing configuration with U-Boot instead of the RaspberryPi
firmware, and both of them worked. I guess that leaves us with a
bootloader bug, and nothing related to Linux after all.

Sorry for the noise,
Maxime