Re: PROBLEM: boot hang on ASUS P2B-F (regression)

[Yazen Ghannam]

On Sun, Mar 22, 2026 at 11:10:45AM -0400, Nick Bowler wrote:
> On Sat, Mar 21, 2026 at 10:52:24PM +0100, Borislav Petkov wrote:
> > Anyway, since you're partially reverting, can you pls try reverting the
> > Intel-relevant hunks and narrow it down, if possible.
> >
> > From the looks of it, I'm thinking:
> > 
> > * comment out the intel_apply_cpu_quirks() call
> > 
> > * comment out this hunk
> > 
> >         /*
> >          * There are also broken BIOSes on some Pentium M and
> >          * earlier systems:
> >          */
> >         if (c->x86_vfm < INTEL_CORE_YONAH && mca_cfg.bootlog < 0)
> >                 mca_cfg.bootlog = 0;
> 
> Making these changes does not appear to have any effect.
> 
> I whittled down the revert to the following patch, and this is
> sufficient to get the machine booting again:
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index 8dd424ac5de8..83eb037d4d46 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -2284,6 +2284,12 @@ void mcheck_cpu_init(struct cpuinfo_x86 *c)
>  
>  	__mcheck_cpu_cap_init();
>  
> +	{
> +	struct mce_bank *mce_banks = this_cpu_ptr(mce_banks_array);
> +	if (c->x86_vfm < INTEL_NEHALEM_EP && this_cpu_read(mce_num_banks))
> +		mce_banks[0].init = false;
> +	}
> +

Hi Nick,

Can you please test after enabling CONFIG_X86_MCE_INTEL?

Without this, the Intel-specific code, including this quirk, will not be
built.

Thanks,
Yazen