On Wed, 2008-07-09 at 14:59 -0500, James Bottomley wrote: > On Wed, 2008-07-09 at 21:22 +0200, Miquel van Smoorenburg wrote: > > On Wed, 2008-07-09 at 14:13 -0500, James Bottomley wrote: > > > On Wed, 2008-07-09 at 21:06 +0200, Miquel van Smoorenburg wrote: > > > > On Wed, 2008-07-09 at 16:49 +0100, Alan Cox wrote: > > > > > On Wed, 09 Jul 2008 15:15:14 +0100 > > > > > David Howells <dhowells@xxxxxxxxxx> wrote: > > > > > > > > > > > Miquel van Smoorenburg <miquels@xxxxxxxxxx> wrote: > > > > > > Maybe, but have you looked at i2o_cfg_passthru()? Take this, for example: > > > > > > > > > > > > /* Allocate memory for the transfer */ > > > > > > p = kmalloc(sg_size, GFP_KERNEL); > > > > > > ... > > > > > > //TODO 64bit fix > > > > > > sg[i].addr_bus = virt_to_bus(p); > > > > > > > > > > > > That looks distinctly dodgy. virt_to_bus() returns a 64-bit address, and as > > > > > > > > > > Agreed - stick | GFP_DMA32 on the end then ;) > > > > > > > > GFP_DMA32 doesn't work with kmalloc(), you need dma_alloc_coherent() or > > > > pci_alloc_consistent() [here, i2o_dma_alloc() ] > > > > > > Yes it does ... it was specifically designed for it. GFP_DMA32 was > > > introduced to allow this type of thing to happen (in the old days most > > > drivers were allowed to assume kmalloc would return memory whose > > > physical address was < 4GB; GFP_DMA32 allows that to continue while > > > allowing kmalloc to stray beyond 4GB physical). > > > > If you use alloc_pages(), yes. But not for kmalloc(). There are no > > general GFP_DMA32 slabs. > > No ... it's platform specific. Platforms whose ZONE_NORMAL covers only > up to 4GB need do nothing. However, x86_64 definitely implements > ZONE_DMA32 for precisely this. Several other platforms (like ia64) > should but don't. I tried using it before (for dpt_i2o.c) and it didn't work. I re-read quite a bit of kernel code before I posted this, and I could not find GFP_DMA32 slabs. There are also no calls to kmalloc(size, GFP_...|GFP_DMA32) in the recent kernels I checked. And google tells me things like http://lkml.org/lkml/2007/5/17/267 So I don't think GFP_DMA32 works with kmalloc. GFP_DMA does though. Mike. -- 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
