[OpenBIOS] Sparc64 memory allocation problem

Mark Cave-Ayland mark.cave-ayland at siriusit.co.uk
Wed Aug 25 18:46:17 CEST 2010

Blue Swirl wrote:

>> Hmmm I didn't think that elf_load() should be being called by the openBSD
>> IEEE-1275 bootblock at all (it looks like the source just opens the file as
>> a standard device) - is it?
> Yes, I think the problem is with the next stage loader.

I took a quick look at the openBSD loader again, and it appears that it 
moves load-base up to 0x6000 and then calls init-program which would 
imply that init-program should sometimes claim the memory, and sometimes 
not :(  A quick play with openBSD 4.7 seems to show the problem has been 
fixed there, which made me think they are relying on another assumption.

I did find an interesting comment in the OpenSolaris bootblock source 

\ OBP doesn't allocate memory for elf
\ programs, it assumes they'll fit
\ under the default 10MB limit

Does that mean there should be a default mapping on SPARC64 whereby the 
first 10MB of memory (0 - 0xa00000), both physical and virtual, are 
mapped together? This would explain why openBSD loads at 0x800000, and 
by doing this we would mark that region of physical memory as being used 
which means the phys_mem allocator would then choose somewhere different...



Mark Cave-Ayland - Senior Technical Architect
PostgreSQL - PostGIS
Sirius Corporation plc - control through freedom
t: +44 870 608 0063

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

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