On Thu, May 01 2008 at 20:33 +0300, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 2008-05-01 at 20:06 +0300, Boaz Harrosh wrote: >> On Thu, May 01 2008 at 19:38 +0300, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: >> <snip> >>> Er, but >>> >>> 1. struct cmdinfo is stack allocated; you can't dma to stack >>> 2. even if you fix this, the structure is packed and will have the >>> original ppc coherence issues >>> 3. Finally, even on the stack, it's not necessarily reachable with >>> the DMA mask >>> >> Ho, thanks for the catch. I really goofed here. >> >>> The whole point of managing sense buffer allocations centrally is to >>> prevent driver writers from falling into all these traps. I really >>> don't think going back to hand rolled bounce buffering imporves the >>> situation. >>> >> We don't have a choice Andi is removing all this. ISA is becoming >> ISA's driver private problem. > > No he's not .. not if it's going to cause this type of grief. > > But I think you misread his patch set. He still has a flag equivalent > of unchecked_isa_dma it's just called sense_buffer_isa instead. The > shift in his patch set is > > 1. it removes the need to allocate commands in dma'able memory > 2. it removes the need for the ULD request path to allocate in > dma'able memory (it uses the block bounce path instead) > 3. it *can't* remove the need to dma to the sense buffer, hence the > flag. > > So it looks like the re-rolled patch set (when Andi gets around to > posting it) will use one pool for the cmd buffer, but separate isa and > non-isa pools for the sense buffer. Thus it should just work for gdth > with scsi_allocate_command predicated on sense_buffer_isa. > > James > I know all about Andi's patches, since I offered to help him as I have some experience with scsi drivers. And it will be me that will post the next round of ISA patches. I have the complete body of work here: http://git.open-osd.org/gitweb.cgi?p=open-osd.git;a=shortlog;h=boaz_sense_effort I planed to first submit up to the Remove-ISA-dma tag and only then RFC and try to push the rest of the work. In the new ISA patchset we got rid of the sense_buffer_isa and converted all ISA drivers to take care of their own sense problems. Which is much more simple then one might think. This is because of 2 reasons. 1 - because to support it in Andi's new mask allocation scheme was an hack, and 2 because I wanted to get rid of them anyway. I apologize in advance for any grief the all effort might cause, and I try to take it upon myself to do all the work, I will very much appreciate any review, thanks for your help already. Boaz -- 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
