Re: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, 2007-07-13 at 15:25 +0200, Geert Uytterhoeven wrote:
> kmap() just returns page_address() on ppc64, as there's no highmem.
> kunmap() is a no-op.

> So technically I could just use page_address() directly, but Christoph
> wanted
> me to keep the kmap()/kunmap() sequence because it's considered a good
> practice.

The point isn't what kmap and kunmap do ... it's the addresses they
return.  By and large, a kernel virtual address for a page is different
from the user virtual address.  If the cache is virtually indexed you
get different cache lines for the same page ... and that sets you up
with aliases you need to resolve.  parisc is the same ... our
kmap/kunmap are nops as well, but our kernel virtual addresses are still
different from the user virtual ones.

James


-
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/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux