lkml.org 
[lkml]   [2007]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch 5/6] ps3: BD/DVD/CD-ROM Storage Driver
On Fri, 13 Jul 2007, James Bottomley wrote:
> 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.

IC.

- flush_kernel_dcache_page() is a no-op on ppc64
(ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE is defined on parisc only).

- For reference, drivers/scsi/ipr.c (another ppc64 driver) just uses a plain
kmap/memcpy/kunmap sequence

So what should I do?

With kind regards,

Geert Uytterhoeven
Software Architect

Sony Network and Software Technology Center Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone: +32 (0)2 700 8453
Fax: +32 (0)2 700 8622
E-mail: Geert.Uytterhoeven@sonycom.com
Internet: http://www.sony-europe.com/

Sony Network and Software Technology Center Europe
A division of Sony Service Centre (Europe) N.V.
Registered office: Technologielaan 7 · B-1840 Londerzeel · Belgium
VAT BE 0413.825.160 · RPR Brussels
Fortis Bank Zaventem · Swift GEBABEBB08A · IBAN BE39001382358619
\
 
 \ /
  Last update: 2007-07-13 15:48    [from the cache]
©2003-2011 Jasper Spaans. Advertise on this site