[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] IDE busmaster DMA support
From: |
Juergen Keil |
Subject: |
Re: [Qemu-devel] IDE busmaster DMA support |
Date: |
Fri, 30 Sep 2005 14:04:45 +0200 (CEST) |
> I'm trying to write an IDE driver with busmaster DMA support.
> My problem is that I can't get the right controller registers addresses.
>
> In the IDE BusMaster DMA specification :
>
> "The control registers for the controller are allocated via the
> devices Base Address register at offset 0x20 in PCI configuration
> space."
>
> If I read the word at offset 0x20 in the PCI configuration space, I get
> 0xc001. But if I boot qemu with a linux live-cd, it tells me that BM-DMA
> is at 0xc000
>
> Do I have to init the PCI IDE controller or something ?
Bit 0 encodes if the registers are in IO (1) or in memory (0) space.
You get the IO base address by using a 0xfffffffe mask.
For memory space the mask is 0xfffffff0, the low four bits encode
a few memory properties (prefetch, 32-bit vs. 64-bit memory addresses).
See the PCI spec for more details. Or for example the PCI_BASE_* defines here:
http://cvs.opensolaris.org/source/xref/usr/src/uts/common/sys/pci.h#519