On Tue, 2007-10-09 at 01:25 +1000, Nick Piggin wrote: > On Tuesday 09 October 2007 16:40, Huang, Ying wrote: > > > +unsigned long copy_from_phys(void *to, unsigned long from_phys, > > + unsigned long n) > > +{ > > + struct page *page; > > + void *from; > > + unsigned long remain = n, offset, trunck; > > + > > + while (remain) { > > + page = pfn_to_page(from_phys >> PAGE_SHIFT); > > + from = kmap_atomic(page, KM_USER0); > > + offset = from_phys & ~PAGE_MASK; > > + if (remain > PAGE_SIZE - offset) > > + trunck = PAGE_SIZE - offset; > > + else > > + trunck = remain; > > + memcpy(to, from + offset, trunck); > > + kunmap_atomic(from, KM_USER0); > > + to += trunck; > > + from_phys += trunck; > > + remain -= trunck; > > + } > > + return n; > > +} > > > I suppose that's not unreasonable to put in mm/memory.c, although > it's not really considered a problem to do this kind of stuff in > a low level arch file... > > You have no kernel virtual mapping for the source data? >
On 32-bit platform such as i386. Some memory zones have no kernel virtual mapping (highmem region etc). So I think this may be useful as a universal way to access physical memory. But it can be more efficient to implement it in arch file for some arch. Should this implementation be used as a fall back implementation with attribute "weak"? > Should it be __init? > > Care to add a line of documentation if you keep it in mm/memory.c? > OK, I will add the document in the next version. Best Regards, Huang Ying - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/