Re: [Xen-devel] Re: [Patch] Constrain DMADOM/swiotlb allocations to 1G phys to fix b44 NIC driver

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 28/11/06 16:31, "Alan" <alan@xxxxxxxxxxxxxxxxxxx> wrote:

>> The 30 bit constraint is enough to let b44 work.  But there are a number
>> of sound cards which require a 28-bit DMA mask (256MB max physical
>> addressable memory).  1GB seems reasonably safe, but I'm much less
>> comfortable with restricting DMADOM to 256MB by default.  Does anyone
>> have any strong feelings about shifting this?  What other users of
>> DMADOM are there that might overflow if we restrict it even further?
> 
> For modern hardware the constraints are primarily the 30/31bit ones found
> on some devices that know too much about Windows. The older sound cards
> with 28bit limits like the ESS Maestro series are very much "old tech"
> now. 

Then it sounds like the restriction to a 1GB DMA pool is a reasonable
one-off change rather than the thin end of a wedge.

 -- Keir


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