Messages in this thread | | | Date | Sun, 20 May 2001 19:37:55 +0200 | From | Andrea Arcangeli <> | Subject | Re: alpha iommu fixes |
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On Sun, May 20, 2001 at 01:16:25PM -0400, Jeff Garzik wrote: > Andrea Arcangeli wrote: > > > > On Sun, May 20, 2001 at 03:49:58PM +0200, Andrea Arcangeli wrote: > > > they returned zero. You either have to drop the skb or to try again later > > > if they returns zero. > > > > BTW, pci_map_single is not a nice interface, it cannot return bus > > address 0, > > who says? > > A value of zero for the mapping is certainly an acceptable value, and it > should be handled by drivers.
this is exactly why I'm saying pci_map_single currently is ugly in declaring a retval of 0 as an error, because as you also explicitly said above bus address 0 is perfectly valid bus adress, so my whole point is that I'd prefer to change the API of pci_map_single to notify of faliure not returning 0 like it does right now in 2.4.5pre3 and all previous 2.4 kernels but via a parameter, so bus address zero returns a valid bus address as it should be just now (but it isn't right now).
> In fact its an open bug in a couple net drivers that they check the > mapping to see if it is non-zero...
if a driver is catching the faluire of pci_map_single by checking if the bus address returned is zero such driver is one of the few (or the only one) correct driver out there.
As it stands right now a bus address of 0 means pci_map_single failed.
For pci_map_sg if it returns zero it means it failed too.
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