[OpenBIOS] Bug in ESP DMA implementation?

[Mark Cave-Ayland]

Blue Swirl wrote:

>> I notice from the code above there is an explicit comment that mentions
>> clearing interrupts to prevent the guest from seeing them so I would have
>> thought that this wouldn't be an issue? I've checked the espdma structures
>> to ensure that they are marked volatile (or _volatile_) and this appears to
>> be the case - so I'm a little bit stumped. Can anyone point me in the right
>> direction or spot the mistake?
> 
> One tricky case was that when allocating memory for IOMMU, the
> alignment restrictions concern physical memory, not virtual.

Wow that was it - forcing physical alignment (as well as virtual 
alignment) seems to resolve the issue - thanks a lot! :)

After a fairly heavy hacking session I now have a version of SPARC32 
OpenBIOS that runs under OFMEM! Initial tests show that Solaris 8 boot 
doesn't get any further, but it's such a tremendous step forward having 
everything using the same ofmem code (and the debugging that comes with 
it), and means that when we fix up the various /memory and 
/virtual-memory properties then they get fixed on ALL platforms.

I think the best thing to do will be to post 2 different patch sets - 
the first containing the OFMEM changes, and the second for the actual 
conversion just to make sure it doesn't cause any regressions.

Note that for this patchset I've taken Andreas' advice and am using git 
for the first time so please go easy on any mistakes in this area :)


ATB,

Mark.

-- 
Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
http://www.siriusit.co.uk
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs