Re: port-amd64/60873: amdgpu enabled Kernel crash

["Heppler, J. Scott via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR port-amd64/60873; it has been noted by GNATS.

From: "Heppler, J. Scott" <shep971%spectrum.net@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: port-amd64/60873: amdgpu enabled Kernel crash
Date: Thu, 15 Oct 2026 15:56:42 -0700

 Just got the automated gnats instructions:
 
 crash:
 _kvm_kvatop(0)
 Kernel compiled without options LOCKDEBUG
 crash _kvm_kvatop(3)
 crash:  cannot read *panicstr: ...
 
 gdb:
 Cannot access memory at 0x473c987027ebde91
 
 If needed I can build a kernel w/ debugging.
 
 On Oct 15, 2026: 22:30, Taylor R Campbell via gnats wrote:
 >The following reply was made to PR port-amd64/60873; it has been noted by GNATS.
 >
 >From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
 >To: gnats-bugs%netbsd.org@localhost
 >Cc: port-amd64-maintainer%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
 >	netbsd-bugs%netbsd.org@localhost, shep971%spectrum.net@localhost
 >Subject: Re: port-amd64/60873: amdgpu enabled Kernel crash
 >Date: Thu, 15 Oct 2026 22:25:46 +0000
 >
 > > Date: Thu, 15 Oct 2026 15:01:20 -0700
 > > From: "Heppler, J. Scott" <shep971%spectrum.net@localhost>
 > >=20
 > > I'm not sure the hand-held photo of the crash was helpful.
 > >=20
 > > Here is the hand transcribed dmesg leading up to the crash:
 > > "[drm] kiq ring mec 2 pipe 1 q 0
 > > panic: fpudna from kernel . ip 0xffffffff807b459b, trapframe 0xffff868827=
 > 064ba0
 > > cpu0: begin traceback
 > > vpanic() at netbsd:vpanic+0x171
 > > panic() at netbsd:panic+0x3c"
 > >=20
 > > If there is anything else that would be helpful, I'll try to generate
 > > it.
 >
 > Are there any lines after that?
 >
 > What's happening is:
 >
 > 1. Something in the kernel is trying to use floating-point/vector
 >    instructions when it is forbidden (`panic: fpudna').
 > 2. There is a stack trace showing what part of the kernel was doing
 >    this.
 > 3. The stack trace as you shared it stops point where the fpu trap
 >    handler called panic(), but I want to see what provoked the fpu
 >    trap handler -- most likely, it's just some small part of the
 >    amdgpu driver that's missing fpu_kern_enter/leave (we've had a few
 >    bugs like this before), but we need to find which part of the
 >    driver that is.
 >
 > Or, did you get a crash dump, e.g. /var/crash/netbsd.N.core?
 >
 > If so, you may be able to get more info out with:
 >
 > $ crash -N /netbsd -M /var/crash/netbsd.N.core
 >
 > or
 >
 > $ gdb /netbsd
 > (gdb) target kvm /var/crash/netbsd.N.core
 > (gdb) bt
 >
 
 -- 
 J. Scott Heppler
 
 Penguin Innovations
 
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