kern/60526: Post-PAE stable SMP machine freezes
sos at DeepCore.dk
Sun Mar 21 12:04:51 PST 2004
Eugene Grosbein wrote:
> On Sun, Mar 21, 2004 at 10:51:10AM +0100, S?ren Schmidt wrote:
>>>Next, Linux seem to have a workarond(?) since 2002:
>>>Soren, could you please look at this?
>>That fix newer worked AFAIK, today linux just dont allow UDMA on the
>>ROSB4 at all.
>>There is no good SW fix, and its also not established that a HW fix
>>exists as well, however I cannot reproduce the problem on my ASUS
>>CUR-DLS engineering sample, but ASUS wont tell anything about it...
> Ok, I've got it.
> Here come two related interesting questions:
> 1. Is it possible to disable secondary ATA channes for FreeBSD completely?
> And have IRQ 15 free for other devices.
As far ATA goes you can share irq15 but lots of HW cant do that. If you
can disable the HW in the BIOS ATA wont pick it up, the ASUS CUR-DLS can
do that, YMMV...
> 2. What is ata(4)'s BIOSDMA and is it possible to use it instead of PIO
> mode? I remebmer times of 2.2.x and 3.x when controller wdc used
> some kind of DMA but not UDMA.
BIOSDMA is still DMA, its named that way since ATA isn't able to tell
what mode it can use, it can just tell that DMA is possible and working.
So ATA just uses DMA commands but has no way of knowing what mode the HW
is operating in, and depends on the BIOS having set up things the right
way. Mostly you will get the mode that the BIOS show on the startup
screen for each device, and that you in some cases can set in the BIOS
setup as well.
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