Re: A DMA patch for linux 2.2.9

Alan Cox (alan@lxorguk.ukuu.org.uk)
Fri, 9 Jul 1999 00:51:14 +0100 (BST)


> > to indicate if the architecture has the DMA memory limit and each
> > architecture can turn it off at the runt-time. We then can do
>
> Some PCI devices (eg Trident 4dwave-NX) have limited address space for DMA
> registers (eg it can only address 1gb memory). So on really large machines
> (eg 2gb) it is still possible to run out of DMA memory. 8)

This is (unfortunately) very common on PCI cards aimed solely at the PC
market. We have for example..

ES1370 top 4 bits of irq registered wired to 0
ESS Maestro 27bit addressing limit. All audio dma buffers within
4 256K chunks

Alan

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