Re: [NAK] Re: [PATCH -v2 9/9] ACPI, APEI, Generic Hardware Error Source POLL/IRQ/NMI notification type support

Ingo Molnar
2010-10-26T10:03:57Z

* Huang Ying <ying.huang@intel.com> wrote:

> On Tue, 2010-10-26 at 15:55 +0800, Ingo Molnar wrote:
> > * Huang Ying <ying.huang@intel.com> wrote:
> >
> > > On Tue, 2010-10-26 at 15:22 +0800, Ingo Molnar wrote:
> > > > * Thomas Gleixner <tglx@linutronix.de> wrote:
> > > >
> > > > > >From Kconfig:
> > > > >
> > > > > EDAC is designed to report errors in the core system.
> > > > > These are low-level errors that are reported in the CPU or
> > > > > supporting chipset or other subsystems:
> > > > > memory errors, cache errors, PCI errors, thermal throttling, etc..
> > > > > If unsure, select 'Y'.
> > > > >
> > > > > So please explain why your error reporting is so different from the above that it
> > > > > justifies a separate facility. And you better come up with a real good explanation
> > > > > other than we looked at EDAC and it did not fit our needs.
> > > >
> > > > Btw., it's not just about EDAC - the firmware can store Linux events
> > > > persistently (beyond allowing the firmware to insert its own RAS events), that
> > > > is obviously _hugely_ useful for kernel debugging in general. We could inject
> > > > debugging events there and recover them after a crash, etc.
> > >
> > > Yes. It can be used by other kernel subsystems other than RAS. A kernel API is
> > > provided already. The design of the kernel API makes it easy to be used by various
> > > kernel subsystems. As the first step, we plan to support saving kernel log before
> > > panic and reading it back after reboot.
> >
> > And that's the problem: we have good facilities already that deal with similar
> > things. We have NMI-safe event logging, event enumeration, dump-on-panic code
> > and all sorts of goodies there.
>
> We have provided an in-kernel API for ERST now. And we plan to implement a
> kmsg_dumper with ERST. And maybe implement some output support (maybe via some
> /dev/kmsg extension) for kmsg_dumper if necessary.

So my argument/objection was:

" You are introducing a bad ABI here, amongst other problems. Please work with the
people who are maintaining sane RAS/event/error reporting ABIs and facilities.
You should have done that to begin with. "

and your answer to that is:

" Hey, we plan to introduce another ad-hoc ABI as well! "

... do you really not see the glaring disconnect?

Ingo