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Date: Fri, 24 Apr 2026 21:50:44 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Christian Zigotzky <chzigotzky@xenosoft.de>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, kvm@vger.kernel.org,
        "debian-powerpc@lists.debian.org" <debian-powerpc@lists.debian.org>,
        "R.T.Dickinson" <rtd2@xtra.co.nz>, hypexed@yahoo.com.au,
        mad skateman <madskateman@gmail.com>,
        Christian Zigotzky <info@xenosoft.de>
Subject: Re: KVM-PR no longer works when compiled with new GCC compilers
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In-Reply-To: <d9ad0cd6fa640f23c396778bce2aa322e40e7e88.camel@physik.fu-berlin.de>

On Fri, Apr 24, 2026 at 05:48:37PM +0200, John Paul Adrian Glaubitz wrote:
> On Fri, 2026-04-24 at 16:47 +0200, Christian Zigotzky wrote:
> > I compiled it with "mtune=power4" today but without any success.
> > 
> > Error messages:
> > 
> > [  800.274759] Couldn't emulate instruction 0x00000000 (op 0 xop 0)
> > [  800.274767] kvmppc_exit_pr_progint: emulation at 100 failed (00000000)
> 
> What exactly are you running inside the KVM? 0x00000000 doesn't seem like
> a valid instruction and a quick Google research reveals that this triggers
> a SIGLL trap.

By definition anything with primary op 0 (the first six bits 0) is
invalid.  It isn't super unusual to (accidentally) try to execute a zero
as an instruction ;-)


Segher