On Sun, Nov 16, 2008 at 11:56:21AM -0500, James Bottomley wrote: > On Sun, 2008-11-16 at 00:11 +0100, Andi Kleen wrote: > > That patch is a little more complicated than the others. advansys > > was the only ISA driver who actually passed ->cmnd to the firmware. > > So I implemented a simple own bounce buffer scheme for this case. > > Also did sense_buffer bouncing in the driver while I was at it; > > which means it doesn't require the mid layer to do this anymore. > > > > - allocate hostdata with GFP_DMA separately for the ISA case > > - Tell block layer explicitely to bounce for ISA case > > - remove unchecked_isa_dma > > > > Untested due to lack of hardware > > > > v2: use dma api for all allocations > > Just a minute: this is another driver where you allocate coherent > memory for the host structure but fail to use it for I/O as far as I can > tell. > > What's going on here? If this is just a ploy to get GFP_DMA memory, > then this isn't the way to do it. Firstly, it doesn't seem to be needed It's just that the structure was in GFP_DMA before due to unchecked_isa_dma so I wanted to do a equivalent convertion > and secondly, coherent memory is hard (or impossible) to manufacture on > certain platforms. You should only use it for DMA mailboxes and other > register exchanges between the device and main memory ... expanding its > use is asking for resource exhaustion. It's not expanding it, in fact it lowers it because they allocate less in GFP_DMA now than with unchecked_isa_dma (e.g. no more commands and sense buffers) -Andi -- ak@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
