Re: [PATCH v6 6/6] alpha: stop on fatal Tsunami system ECC and write parity errors

[Magnus Lindholm]

Hi Matt,

On Tue, Oct 13, 2026 at 5:20 AM Matt Turner <mattst88@xxxxxxxxx> wrote:
>
> On Mon, Oct 12, 2026 at 12:58 AM Magnus Lindholm <linmag7@xxxxxxxxx> wrote:
> >
> > Hi Matt,
> >
> > On Sun, Oct 11, 2026 at 10:01 PM Matt Turner <mattst88@xxxxxxxxx> wrote:
> > >
> > > > +#define TSUNAMI_PERROR_FATAL (perror_m_uecc | perror_m_perr)
> > >
> > > Why PERR and not RDPE? Bad parity on data read from PCI seems just as
> > > bad for the consumer. If the HRM says the Pchip poisons that data and
> > > the CPU takes a 670 for it, please say so in the changelog.
> > >
> > > > +             perror = live.perror[0] | live.perror[1];
> > >
> > > The changelog says incidental PERROR state on a CPU or environmental
> > > vector cannot trigger the panic. It still can on a system vector: UECC
> > > or PERR latched before an unrelated NXM will panic here. That may be
> > > what you want, since the error is real either way, but the changelog
> > > should cover it. It also depends on the PERRMASK question I asked on
> > > patch 4.
> > >
> > > Two things that I think belong in the changelog:
> > >
> > > A CPU-detected uncorrectable ECC error (670 through
> > > ev6_machine_check()) still does not panic, so after this patch the
> > > policy differs by who detected the error.
> > >
> > > A PCI card with a marginal connection that asserts PERR# now takes the
> > > machine down, where before it logged and carried on.
> >
> > Thanks, these are good points. Would it make sense to drop patch 6
> > for now and address the panic policy in a follow-up? That would let
> > us consider RDPE, CPU-detected ECC and previously latched errors
> > alongside UECC/PERR, including the impact of a device asserting PERR#.
> >
> > V7 could then focus on the reporting and acknowledgment improvements.
> > That would preserve the existing continuation behavior for now,
> > without implying that continuing after an uncorrectable error is safe.
> >
> > Magnus
>
> Yeah, that seems reasonable to me.

I'll put out a v7, focusing on reporting and acknowledgment
improvements, preserving the existing continuation behavior.


Regards,
Magnus