CONFIG_KDB_KEYBOARD

[Valdis Kl=?utf-8?Q?=c4=93?=tnieks]

On Mon, 03 Aug 2020 11:30:05 -0600, jim.cromie at gmail.com said:

> I notice this excludes USB keyboard.
>
> does this mean it doesnt work early enough to be useful for early panics etc?

Very early panics and hangs are always a royal pain to deal with.  There's no
really good way to deal with it, because let's face it - if the operating
system hasn't gotten its act together yet, it's going to have a hard time
talking to you unless you can run it in a virtual machine or similar that has
the tooling to allow you to usefully explore the memory entrails.

> what does it mean for a panic right after starting 2nd CPUs ?

> [    0.416908] kthreadd invoked oom-killer: gfp_mask=0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GF
> gfp_mask=0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_ZERO), order=0, oom_score_adj=0
> [    0.417551] CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.8.0-rc7-00023-gede6954dc460-dirty #101
> [    0.418541] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014

Hitting the OOM killer on PID 2 in QEMU sounds suspiciously like you started
QEMU and specified an insanely small memory space for the image.

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