linux-kernel - Re: x86: Boot failure on select chromebooks with v6.15-rc5

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aB2bStp8efMHPjet@gmail.com>
Date: Fri, 9 May 2025 08:06:02 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Vignesh Raman <vignesh.raman@...labora.com>
Cc: dmukhin@...d.com, mingo@...hat.com, andriy.shevchenko@...ux.intel.com,
	x86@...nel.org, daniels <daniels@...labora.com>,
	Daniel Stone <daniel@...ishbar.org>,
	robdclark <robdclark@...il.com>, lumag@...nel.org,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: x86: Boot failure on select chromebooks with v6.15-rc5


* Vignesh Raman <vignesh.raman@...labora.com> wrote:

> Hi,
> 
> With v6.15-rc5, the below chromebooks were not booting with the following
> message. These tests were run in drm-ci.
> 
> Starting kernel ...
> [    1.843801]  ? __pfx_kernel_init+0x10/0x10
> [    1.909838]  ? __pfx_kernel_init+0x10/0x10
> 
> https://gitlab.freedesktop.org/vigneshraman/linux/-/pipelines/1420485
> 
> Failing jobs:
> amdgpu:stoney (AMD Stoney Ridge chipset):
> https://gitlab.freedesktop.org/vigneshraman/linux/-/jobs/76000926
> 
> i915:amly (64 bit Intel Whiskey Lake):
> https://gitlab.freedesktop.org/vigneshraman/linux/-/jobs/76000929
> 
> i915:whl (64 bit Intel Amber Lake):
> https://gitlab.freedesktop.org/vigneshraman/linux/-/jobs/76000931
> 
> These tests were passing till v6.14-rc7, and the issue was seen starting in
> v6.15-rc1. This issue is seen only with these 3 boards and does not affect
> other chromebooks (the pipeline log shows the other i915 driver tests).
> 
> On bisecting the commits, the commit which introduced this issue is,
> 3181424aeac2f6596534bf43021a10eae294a9b0 x86/early_printk: Add support for
> MMIO-based UARTs
> 
> After reverting the below commits in v6.15-rc5, the board boots and tests
> are executed:
> 3181424aeac2 x86/early_printk: Add support for MMIO-based UARTs
> 996457176bb7 x86/early_printk: Use 'mmio32' for consistency, fix comments
> (this fixes 3181424aeac2)

What boot cmdline does your kernel have? The MMIO-UART patches should 
only have an effect if the feature is specifically enabled via a boot 
option:

+               if (!strncmp(buf, "mmio32", 6)) {
+			buf += 6;
+                       early_mmio_serial_init(buf);
+                       early_console_register(&early_serial_console, keep);
+                       buf += 4;
+               }

The only other change I can see is the moving of an #if line.

Thanks,

	Ingo