Re: AW: [REGRESSION] x86/microcode: boot hangs bringing up first secondary CPU on i7-6700HQ, avoided by dis_ucode_ldr

[Thorsten Leemhuis]

On 11/9/26 22:09, Dario Ackermann wrote:
> I found two similar reports on ASUS N552V-series laptops with an Intel i7-6700HQ:

FWIW, the earlier report from Dario was here:
https://lore.kernel.org/all/581128204058725416570264.8152.2026119193410@xxxxxxxxxxxxxxxxx/


> Ubuntu N552VW: the reporter tested upstream 6.4.0 as working and 6.5.0 as failing. Boot stopped at "smpboot: x86: Booting SMP configuration:", and dis_ucode_ldr allowed booting.
> https://askubuntu.com/questions/1512327/ubuntu-freezes-during-boot-when-using-linux-kernel-6-5-0
> 
> openSUSE N552V: the reporter says 6.1 works, newer kernels hang when Intel microcode is present, and dis_ucode_ldr allows booting.
> https://forums.opensuse.org/t/opensuse-tw-wont-boot-without-the-dis_ucode_ldr-parameter/175229
> 
> Commit 0c7ffa32dbd6 ("x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it"), merged for 6.5, moved AP microcode loading from after the AP startup handshake to before it. This is a candidate cause, not yet confirmed by a bisect or patched-kernel boot test on my N552VX.
> https://git.kernel.org/linus/0c7ffa32dbd6b09a87fea4ad1de8b27145dfd9a6
> 
> I am preparing two upstream 6.18.55 boot images, one unmodified and one with the AP microcode call moved after the handshake, for a direct comparison and to work on a potential fix

FWIW, you really want to test with at least 7.3 or, which would way
better, latest mainline (7.4-rc2 or newer), as the bug might be fixed
there already. If not, some developer might come around with an idea to
debug it; if that doesn't work out, you most likely will need to bisect
the problem.

Ciao, Thorsten