Re: [Qemu-devel] MMIO coalescing of the i82378 bridge

[Andreas Färber]

Hi Jan,

Am 23.06.2012 11:28, schrieb Jan Kiszka:
> just stumbled over the memory_region_set_coalescing in pci_i82378_init:
> What ISA devices are affected by this? It looks a bit strange to me as
> the MMIO requests are apparently mapped on PIO requests, and we don't
> have PIO coalescing on x86. Depending on the target device on PREP, this
> may have some unexpected side effects. Or is only framebuffer memory
> addressed this way?

I only remember touching that line to rebase it onto either Memory API
or QOM. The i82378 is the sole PCI-ISA bridge so all ISA devices will be
affected by it, which is pretty much everything except VGA iirc.
The upcoming pc87312(?) Super I/O also would be attached to it,
replacing some of the bogus I/O in the current "prep" machine.

I'm not familiar with what this option affects. What unexpected side
effects would you expect? :)

Regards,
Andreas