Re: unchecked_isa_dma and BusLogic SCSI controller

From: Matthew Wilcox
Date: Thu Nov 02 2006 - 07:41:52 EST


On Wed, Nov 01, 2006 at 05:33:58PM -0800, Randy Dunlap wrote:
> unchecked_isa_dma - 1=>only use bottom 16 MB of ram (ISA DMA addressing
> restriction), 0=>can use full 32 bit (or better) DMA
> address space
>
> > It is hard for me to see why BusLogic controller would only do DMA
> > in low 16MB. Is there a fix for this?
>
> Does anyone know that controller hardware and its limitations?

I don't, but:

if (pci_set_dma_mask(PCI_Device, DMA_32BIT_MASK ))
continue;

So somebody thinks the device can do 32-bit addressing. I would expect
that setting unchecked_isa_dma is a historical mistake. However, I
don't have any cards of this type to test.

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