Re: proposed cpuctl modification

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Fri, 03 Mar 2023 09:25:29 +1100
    From:        matthew green <mrg%eterna.com.au@localhost>
    Message-ID:  <14071.1677795929%splode.eterna.com.au@localhost>

  | we should do this as well, it should fairly simple.  we already
  | display the relevant info in "cpuctl identify 0" eg:

Yes, identify shows all of the relevant info (including ucode version)
so all of this can certainly be done - it was just more than I wanted
to do to just suppress the annoying error messages...

  | hmm, someone seems to have broken this recently?

Now you point it out, I am seeing that too.

  | that's odd, but we should handle it saner.

My processor is odd - but it is very fast (in some of the cores anyway).

  | this seems odd to me.  verbose should print additional info
  | but it shouldn't change the actual behaviour here.

When -v is given, the code is intended to operate exactly as it did
before (it will execute a few more instructions, but the effect should
be identical).

  | eg, if i were to use this with -v on your CPU, i'd want to
  | have it show it working on cpu0 and cpu4, and EEXIST for
  | the rest, and this appears that it will exit after cpu1.

That is what it has always done.   It exits after cpu0 as well.
And every other cpu - it only gets asked to update one cpu at a time.
In the Intel case, cpuctl is run on each cpu separately, not to attempt
to update all of them in one run (I'm not even sure that is possible,
or not with the code as it is now).

It has never printed anything (with or without -v) for a
successful microcode update - before my change, the -v flag
appears to do nothing at all, so I wasn't too worried about
borrowing it.   The kernel logs successful ucode updates however.

All the change does, is ignore the EEXIST (and exit 0, not that the
exit status seems to matter to anything, at least as used in rc.d)
when -v is not given (which rc.d does not do), rather than printing
an error and doing exit(1).

I don't have an AMD processor, where things are done differently,
to test this change on though.

kre