Messages in this thread | | | Date | Mon, 18 Oct 1999 01:57:36 -0700 | From | "David S. Miller" <> | Subject | Re: GFP_DMA not good enough for problem hardware |
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Date: Mon, 18 Oct 1999 09:28:08 +0100 From: Giuliano Procida <myxie@debian.org>
I'm sure other driver writers have hit similar problems before. What can I do to fix this?
Sometimes I wish people who make such cards would think twice about putting such restrictions into their PCI addressing logic, even for boot time microcode loading operations.
I say this, because cards like the one you are working on can thus _never_ work in an UltraSparc/PCI based system, because on such systems, in the PCI DMA areas the top bit needs to be set, so all such devices which "chop off" or do not implement the higher PCI addressing bits for bus mastering, will not work on Sparc/PCI.
Note also that this makes such cards out of spec, PCI wise. Many PCI sound cards have these issues as well (most implement the lower 24 bits, and use the upper bits in their DMA descriptors for control information, supposedly to save logic gates in the hw or to simplify it in some other way).
Later, David S. Miller davem@redhat.com
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