On Wed, 2013-01-30 at 11:35 +0000, Russell King - ARM Linux wrote: > On Wed, Jan 30, 2013 at 12:21:21PM +0100, Julia Lawall wrote: > > On Wed, 30 Jan 2013, Russell King - ARM Linux wrote: > > > So, _either_ logical OR or addition works. > > > > > > If we _did_ end up with a PHYS_OFFSET with bits less than bit 26 set > > > here, we'd have bigger problems - because the base of RAM in PCI space > > > will not correspond with PHYS_OFFSET and all the DMA mapping stuff breaks. > > > > The "problem" is that the computation is done inconsistently within the > > same file. Sometimes with + and sometimes with |. > > And I say that is not a problem; if it _does_ become a problem, there are > bigger problems that would also need solving, which given a multi-subarch > kernel become a lot lot harder. > > Sure, we can just change them to all be a bitwise OR (sorry, not logical) > but that's really only half the story. As far as I can tell, there'd be a lot of +'s to change in arch/arm and only 2 uses of | in it8152.c $ git grep -P "\(?\s*SZ_\d+[A-Z]\s*-\s*1\s*\)?\s*\|" arch/arm arch/arm/common/it8152.c: *dev->dma_mask = (SZ_64M - 1) | PHYS_OFFSET; arch/arm/common/it8152.c: dev->coherent_dma_mask = (SZ_64M - 1) | PHYS_OFFSET; $ git grep -P "\+\s*\(?\s*SZ_\d+[A-Z]\b\s*-\s*1\s*\)?" arch/arm | wc -l 460 I think consistently using + would make it simpler for some possible future conversion. -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
