10.1-BETA2 PowerMac G5 panic dump failure: "- oversized DMA transfer attempt 65536 > 32768"

[Mark Millard]

I induced a panic dump attempt well after booting but it reported:

Dumping 606MB (160 chunks)
Chunk 0: 574592 bytes ata2:
failure - oversized DMA transfer attempt 65536 > 32768
...

So it would appear that by default I can not get dumps for panics, at least not on the PowerMac G5 configurations. (I'd guess that the PowerMac G4's would be similar.) Everything else has been working for the SSD use (the only media in place at the time --or normally).


Context:

FreeBSD FBSDG5M1 10.1-BETA2 FreeBSD 10.1-BETA2 #22 r271944M: Sun Sep 28 00:29:03 PDT 2014     root at FBSDG5M1:/usr/obj/usr/src/sys/GENERIC64  powerpc

GENERIC64 with options DDB and GDB added. WITH_DEBUG_FILES= WITHOUT_CLANG= WITH_DEBUG= in /etc/make.conf. Odd DDB hack (internal automatic script definition) for boot time reporting of information to expose what is going on for a PowerMac G5 boot crash that happens fairly frequently --reporting despite no input working at that early stage. Also added a call to report a kernel backtrace at during the first OF_<?> after the mmu is configured, before the actual ofwcall (which may crash).


The panic here was long after booting and logging in and it is from my using Control-option-esc to get into DDB interactively (for the first time) and my experimenting there. I'm not worried about the specific panic at this point. But that dumps will fail is not so good. (It would have been my first kernel dump.)

Also possibly odd is that the only media is an SSD listed as ada0 with partitions/slices listed as various ada0s<?>. Yet the dump failure messages referred to ata2. There is no /dev/ata2 present. The swap partition was on ada0s9 that it should have used for the dump.



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Mark Millard
markmi at dsl-only.net