[coreboot] [RFC] Universal panic-room serial console, for x86 BIOS bootblock

Patrick Georgi patrick at georgi-clan.de
Tue Jul 12 08:02:49 CEST 2011


On Tue, 12 Jul 2011 02:03:46 +0200, Peter Stuge wrote:
> Pete Batard wrote:
>> a minimal xHCI stack
> Note needs DMA, except for EHCI Debug Port, which needs a special 
> device.
EHCI requires a special device and no DMA (but debug port support in 
the EHCI controller).

xHCI requires no special device: if the optional debug port feature is 
provided, everything is inside the controller.
However, xHCI potentially requires memory to be around for DMA: there's 
another optional feature to have the controller provide enough memory in 
MMIO range to do xHCI debug without RAM.

Now I suppose the question is, if there's a PCIe xHCI controller with 
both debug port and MMIO-as-RAM features for a reasonable price? If so, 
all we'd need is a bit of bus poking to make xHCI debug useful for us.


Patrick




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