Re: CVS commit: src/sys/arch/amd64/amd64

[Maxime Villard <max%m00nbsd.net@localhost>]

Le 21/08/2019 à 23:47, matthew green a écrit :
> "Maxime Villard" writes:
> > Module Name:	src
> > Committed By:	maxv
> > Date:		Wed Aug 21 16:35:10 UTC 2019
> >
> > Modified Files:
> > 	src/sys/arch/amd64/amd64: locore.S
> >
> > Log Message:
> > Switch from printf to panic. These messages were notorious for being
> > unreadable, and at least a clean panic allows the user to inspect the
> > system via DDB. Also simplify the output, EAX gets overwritten with
> > the error code so it indicates nothing meaningful.
>
> thanks for this.  i'd been working on the same myself.
>
> do you have a reliable way to trigger this issue?  i thought that
> returning to userland with a lock held would do it, but i wasn't
> able to get that to work reliably.  there's more work related to
> crash dumps i'd like to work on but i got distracted by testing a
> change similar to this one and didn't get back to it yet.

if you hard-code a splhigh() in a syscall and invoke it, you can see
the message; to get the unreadable/garbage output you likely need to
have two threads that invoke the syscall at the same time