Re: [RFC PATCH] x86/apic: Fix BUG due to multiple allocation of legacy vectors.

From: imran . f . khan
Date: Thu May 27 2021 - 01:14:22 EST


Hi Thomas,

On 26/5/21 12:51 am, Thomas Gleixner wrote:
Imran,

On Mon, May 24 2021 at 13:29, imran f. khan wrote:
[...]

Even my current setup that was crashing with in-house 5.4 and 5.8
kernels, boots fine if I boot it with noapic option removed from kernel
boot parameters.

May I ask the obvious question why the changelog of your patch did not
mention that this happens only with 'noapic' on the kernel command line?

I was not aware of it earlier. After your first feedback I debugged the code further with ML tag and found out about the noapic dependency.
[...]

Correct. So you almost decoded the underlying problem.

[...]
So the right thing to do is to ensure that the legacy interrupts are
marked as system vectors in case that the IO/APIC is disabled via
config, kernel command line or lack of enumeration. See below.

Thanks for clarifying it. I have tested your change in my local setup as well and it works well.

Thanks,
Imran