On Thu, 19 Jul 2007 10:49:30 -0700 Randy Dunlap wrote: > On Thu, 19 Jul 2007 18:57:50 +0300 Boaz Harrosh wrote: > > > Randy Dunlap wrote: > > > > > > Yes, this problem has been around forever AFAIK. You didn't add > > > to it. > > Do we need to file a bug report in Bugzilla or something, so people have a > > documentation of the work-around, until it is fixed? > > Wouldn't hurt, I guess, but the SCSI people know about it. > > > I think that for now I will wrap it up as it is. Could you send me the right > > BUG_ON() in place, with a printk pointing users to a solution? and I'll > > redo all the patches. > > I didn't add a BUG_ON(), so I don't have that patch. > (I just used a .slave_alloc function to force no high memory data > addresses, just like ppa.c does.) > > You could just do a BUG_ON() just before there is an outsw() > or insw() to a NULL pointer, e.g., in datao_run: > > BUG_ON(CURRENT_SC->SCp.ptr); > > or we could make building the driver depend on !HIGHMEM. > > I prefer either of the !HIGHMEM or slave_alloc changes to adding > a BUG_ON(). However, the SCSI people likely won't want to use the > slave_alloc() change because then the driver may never get fixed. > (Of course, it hasn't got fixed with the BUG happening either.) > > Anyway, I'll re-read Documentation/DMA*.txt to see if I can fix it. I have asked this once before, but I don't like the answer. Currently aha152x.c only works with !HIGHMEM due to highmem-pages not being mapped into the driver's memory space. James and hch tell me that using DMA mapping functions is the way to fix this, but those appear to me to be for DMA (!!), and this driver is (only) using PIO. I did try to use dma_map_sg() & dma_unmap_sg() here, but they end up giving the driver physical buffer addresses, which aren't what is needed for PIO. Should this driver be using scsi_kmap_atomic_sg() and scsi_kunmap_atomic_sg() or other API functions, or should the driver just use kmap_atomic() + kunmap_atomic() for each highmem page? Thanks, --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** - 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
