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

[Nick Bowler]

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;
+	}
+
 	if (!mce_gen_pool_init()) {
 		mca_cfg.disabled = 1;
 		pr_emerg("Couldn't allocate MCE records pool!\n");