Re: Problems with registers save/restore on context switch?

[Donald Lee <MacPPC2%c.icompute.com@localhost>]

>On 26 December 2013 20:15, Donald Lee <MacPPC2%c.icompute.com@localhost> wrote:
>> I have run the same test (with trivial printf's added to show progress)
>> on a G4, running NetBSD 5.2, AND NetBSD 6.0.2, and it comes through clean.
>>
>> I have included the logs from these two machines. mercy fails. Candor
>> run the test cleanly.
>>
>> I'm not sure what this means, but it seems to imply that the poblem is
>> CPU specific because it works cleanly on the Beige G3, on a certain G4, but
>> not on another (faster, newer) G4
>
>Very interesting find!
>
>(My powerpc skills could probably be listed on the back of a 601 die,
>but some random comments below)

;->

>There are not many MPC7400 vs MPC7447A differences in
>sys/arch/powerpc/oea/cpu_subr.c
>
>There is one 7447A section with the comment /* Enable the 7450 branch
>caches */ which also has /* Disable BTIC on 7450 Rev 2.0 or earlier */
>- I'm pretty sure its irrelevant, but disabling it would be easy to
>test.

Tell me how, and I'll do it.

>The "oea_startup: failed to allocate DEAD ZONE" code has a comment
>which indicates it is harmless, but another difference between the two
>is the amount of memory - would it be possible to test them both with
>the same (lower) amount of memory, such as 512M?

Unfortunately, one of the "test" machines is a production machine, so
that would be..... inconvenient.

I'll see if I have another machine around that fails that I can
mess with.

>The 7440 cache is reported as write back, while the 7447A is not,
>though I suspect that may just be a reporting inconsistency.
>
>The 7440 L2 cache is supposed to be 2-way set associative vs 8-way set
>associative for the 7447A - I don't see any differences in the
>handling code, though I don't know if that is significant...

-dgl-