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

[Vignesh Raman]

Hi Ingo,

On 09/05/25 11:36, Ingo Molnar wrote:
> * Vignesh Raman <vignesh.raman@xxxxxxxxxxxxx> 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;
> +               }

amdgpu:stoney:
earlyprintk=uart8250,mmio32,0xfedc6000,115200n8  console=ttyS0,115200n8 
root=/dev/nfs rw 
nfsroot=192.168.201.1:/var/lib/lava/dispatcher/tmp/18598802/extract-nfsrootfs-wgn1xjer,tcp,hard,v3 
init=/init rootwait usbcore.quirks=0bda:8153:k ip=dhcp 
tftpserverip=192.168.201.1

i915:amly:
earlyprintk=uart8250,mmio32,0xde000000,115200n8  console=ttyS0,115200n8 
root=/dev/nfs rw 
nfsroot=192.168.201.1:/var/lib/lava/dispatcher/tmp/18598804/extract-nfsrootfs-5rlm_b6z,tcp,hard,v3 
init=/init rootwait usbcore.quirks=0bda:8153:k ip=dhcp 
tftpserverip=192.168.201.1

i915:whl:
earlyprintk=uart8250,mmio32,0xde000000,115200n8  console=ttyS0,115200n8 
root=/dev/nfs rw 
nfsroot=192.168.201.1:/var/lib/lava/dispatcher/tmp/18598833/extract-nfsrootfs-3w0w5_mi,tcp,hard,v3 
init=/init rootwait usbcore.quirks=0bda:8153:k ip=dhcp 
tftpserverip=192.168.201.1

Regards,
Vignesh

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