Re: loader lsdev crashes loader (Was: head -r338804 boots threadripper 1950X fine; head -r338810+ do not; -r338807 seems implicated)

From: Konstantin Belousov <kostikbel_at_gmail.com>
Date: Tue, 23 Oct 2018 18:16:39 +0300
On Tue, Oct 23, 2018 at 08:54:24AM -0600, Warner Losh wrote:
> On Tue, Oct 23, 2018 at 5:54 AM Toomas Soome <tsoome_at_me.com> wrote:
> 
> >
> > > On 23 Oct 2018, at 13:53, Lev Serebryakov <lev_at_FreeBSD.org> wrote:
> > >
> > > On 22.10.2018 12:27, Toomas Soome wrote:
> > >
> > >> It would help to get output from loader lsdev -v command.
> > > current loader crashes on "lsdev" for me:
> > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=232483 (it is not
> > > threadripper-related, my hardware is Intel Atom).
> > >
> > > --
> > > // Lev Serebryakov
> > >
> >
> > That error means something is corrupting the memory, it is hard to guess
> > what exactly and debugging it is nasty - it means we would need to track
> > down what was allocated before this memory block (guard1 is marker inserted
> > in front of the allocated memory block).
> >
> > Fortunately the code to print the partition table is in
> > stand/common/disk.c and the partition code is just next to it and so it
> > should be relatively easy to find the guilty oneā€¦ I will try to see if I
> > can replicate the issue.
> >
> 
> We've had reports of other systems mysteriously hanging on boot with the
> new boot loader, but not older ones. It isn't limited to new AMD boxes, but
> it's been seen on other Intel boxes of various flavors. When we crash, it
> seems like we don't have a good recovery like we do with BTX. Maybe they
> are related?

There is the 'grab_faults' command which might be used to get
information about the fault (as in, CPU fault due to the programming
mistake). You need to issue it before doing something that can cause the
fault. It is not enabled by default due to the methods it uses to catch
the exceptions.

I recently noted that at least UEFI 2.7 provides debugging interfaces
which can be used to achieve the same fault interception effect without
hacks.
Received on Tue Oct 23 2018 - 13:16:51 UTC

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