[OpenBIOS] Faulty Qemu SPARC64 IDE emulation?
Tarl.Neustaedter at Sun.COM
Sun Dec 13 19:07:41 CET 2009
Igor Kovalenko wrote:
> We also need to find out how memory mappings are laid out
> preparing to run client code. It is not clear from of1275 docs.
Generally, OF is placed in high memory, and memory allocations are from
But there are several address spaces, which it sounds like are being
1) Actual memory
2) PCI memory space
3) PCI IO space
They are each independent address spaces. Zero in any one of them is
independent from zero in all the others.
Note that PCI memory space is further subdivided into DMA address space
and BAR memory space. In general on SPARC (with Openboot, at least), we
use low addresses in PCI memory space for BARs and high addresses for
DMA (backwards from x86 behaviour). We've found a number of devices
which refuse to allow us to assign PCI memory space 0 to a BAR - so
we've had to reserve the low order page of PCI memory and not assign it
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