[SeaBIOS] ohci bulk?

Stefan Berger stefanb at linux.vnet.ibm.com
Sat Nov 20 18:58:56 CET 2010

On 11/20/2010 12:50 PM, Kevin O'Connor wrote:
> On Fri, Nov 19, 2010 at 03:39:58PM -0800, H. Peter Anvin wrote:
>> On 11/19/2010 02:58 PM, Gerd Hoffmann wrote:
>>> On 09/23/10 14:56, Kevin O'Connor wrote:
>>>> I suppose one could write a simple SMI handler that just set the OHCI
>>>> cmdstatus bits.  That probably wouldn't be too hard and it wouldn't be
>>>> too complex.
>>>     Hi folks,
>>> What is the current state of affairs?  Sooner or later we'll need a
>>> solution for the pci-bar-access-from-real-mode issue ...
>>> I looked briefly at the usb3 specs and I think it is impossible to drive
>>> a xHCI adapter without access to the PCI bar.
> Looking briefly myself, it does look like accessing the doorbell
> registers will be necessary.
>>> Also AHCI support needs access to the PCI bar to submit commands and
>>> check status.
> Yeah - it looks that way to me as well.
>> Would INT 15h, AH=87h do the job well enough?  Otherwise it's probably
>> SMM or bust...
> I don't think int1587 would work reliably.  So, I'd say SMM would be
> needed.
> I suppose one could implement a simple SMM gateway - write a magic IO
> bit to invoke the SMM handler, have the SMM handler backup the cpu
> state somewhere in BIOS owned memory, and then leave SMM mode with
> execution at a BIOS handler running in 32bit flat mode.  The BIOS
> handler could then do its work and manually return the CPU to its
> initial state before returning to the guest.  The BIOS would need to
> ensure that it didn't allow interrupts (or NMIs) while in this mode,
> but that's possible.  One would probably want to ensure that the BIOS
> didn't touch any non-BIOS owned memory in this state as well, but
> that's also possible.
FWIW, I am currently working on a gateway for calling 32 bit functions 
in the relocated 32bit code from 16 bit code, opening up that are for 
more than the init functions. It works fine from what I can see also 
considering the mixture of register and stack passing of arguments. 
Would that be helpful here?

> -Kevin
> _______________________________________________
> SeaBIOS mailing list
> SeaBIOS at seabios.org
> http://www.seabios.org/mailman/listinfo/seabios

More information about the SeaBIOS mailing list