[LinuxBIOS] VGA bios and i/o access for powerpc

jf simon jfaslist at yahoo.fr
Tue Sep 5 12:46:26 CEST 2006

I have read the excellent paper on FreeVGA

and I am thinking on using it on a powerpc design we have made based on 
IBM 970fx ppc64 CPU (after it runs linuxbios of course, but I am trying 
to plan ahead and see what is needed to have PCI graphic cards running 
on it).
I have looked at the x86emu code, and more precisely to the 
X86EMU_pioFuncs  function which is in charge of I/O accesses whenever 
the VGA BIOS makes  an x86 int/out instruction to some I/O port (for 
example to the range of VGA control registers in the 0x3XX region). The 
graphic I intend to use is an ATI Radeon RV100 PCI card. So it looks 
like I will have to program the X86EMU_pioFuncs with  a function that 
will redirect I/O accesses from the low 0x3XX addresses,  to the ATI PCI 
I/O region that contains VGA registers. Here is an excerpt of an "lspci 
-vv" on my graphic card (see below). I am planning to re-direct all 
these  I/O accesses  to the region 1 (I/O ports at f4015000). The VGA 
registers have to be in there...where else?
So it shouldn't be too hard. Am I overlooking things? The FreeVGA paper 
said he should be rather complicated to do on powerpc....so i may be to 

02:01.0 VGA compatible controller: ATI Technologies Inc Radeon RV100 QY 
        Subsystem: ATI Technologies Inc: Unknown device 013b
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- 
ParErr- Ste-
        Status: Cap+ 66Mhz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- 
        Latency: 255 (2000ns min)
        Interrupt: pin A routed to IRQ 30
        Region 0: Memory at 0000000080000000 (32-bit, prefetchable)
        Region 1: I/O ports at f4015000 [size=256]
        Region 2: Memory at 00000000a0000000 (32-bit, non-prefetchable) 
        Capabilities: [50] Power Management version 2
                Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA 
                Status: D0 PME-Enable- DSel=0 DScale=0 PME-

Thanks a lot
-jf simon


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