Hi Zheng,
On 03.05.20 17:27, Zheng Bao wrote:
I am debugging the AMD Picasso board. When Linux kernel boots, there is some error message in dmesg. do_IRQ: 1.55 No irq handler for vector
The kernel can still boot. What does this message mean? Can I just ignore this message?
well, I'm worried. Even if it probably breaks nothing, it seems the APs are not in a state that Linux expects when it starts them up.
1.55 means interrupt vector 55 on CPU#1. This is in Linux' legacy interrupt range, should be IRQ 7 (offset by 48).
That's where my Linux knowledge ended but I just had a quick look: In `arch/x86/kernel/smpboot.c` we have start_secondary() which runs on the AP. It calls:
load_current_idt(); ... lapic_online(); ... local_irq_enable();
A comment above the declaration of load_current_idt() indicates that we don't expect IRQs yet (before local_irq_enable() via `sti` I guess). That the kernel complains "No irq handler for vector" likely means that an interrupt is triggered before lapic_online() registered the handler.
So, for me there are two mysteries:
1. Why is IRQ 7 triggerred?
2. Why does the AP process interrupts before `sti`? (if my assessment above is correct).
Did you run any payload between coreboot and the kernel?
Nico
PS. I didn't thought you'd ask without googling first, there are mailing list threads about the issue already. Let's see what they say...