[Qemu-devel] Newbie: How to implement iommu?

[Brian Wheeler]

I've been going through the source (and the list archives) and I must be
missing something obvious.  

I need to translate an address passed to
cpu_physical_memory_{read,write} via an IOMMU.  I've been told there's a
dma api, but I cannot find any documentation about it, nor can I find an
obvious user of it.

How do I hook into the read/write address translation?  I can see that
the iommu is setup correctly:

typhoon pchip0 read  reg=1, val=0000000080000001
typhoon pchip0 read  reg=5, val=000000003ff00000
typhoon pchip0 read  reg=9, val=0000000000000000

(which basically translates any 32-bit address beginning with 0x80000000
to 0x00000000)

and later in the emulation I'm seeing a bunch of readl messages

Unassigned mem readl 0000000086246ffc

which should have really been looking at physical address 0x6246ffc


So how do I catch cpu_physical_memory_{read,write} calls and put my
address translation in there?


Thanks!
Brian