Messages in this thread | | | Subject | Re: Problem with NETIF_F_HIGHDMA | From | Arjan van de Ven <> | Date | Wed, 22 Feb 2006 19:51:01 +0100 |
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On Wed, 2006-02-22 at 12:47 -0600, Corey Minyard wrote: > I was looking at a problem with a new system we are trying to get up and > running. It has a 32-bit only PCI network device, but is a 64-bit > (x86_64) system. Looking at the code for NETIF_F_HIGHDMA (which, when > not set on a PCI network device, means that it cannot do 64-bit > accesses) in net/core/dev.c, it seems wrong to me. > > It is dependent on HIGHMEM, but HIGHMEM has nothing to do with 32/64 bit > accesses. On 64-bit systems, HIGHMEM is not set, thus the network code > will pass any address (including those >32bits) to the driver. Plus, > highmem on 32-bit systems may very well be 32-bit accessible, possibly > resulting in unecessary copies. AFAICT, the current code will only work > with i386 and PAE and is sub-optim
you use the PCI mapping api right? if you do that then there's no problem, after pci mapping the addresses will be in the lower address range perfectly fine....
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