On Jun 23, 2011, at 7:02 AM, Ralf Baechle wrote: > On Thu, Jun 23, 2011 at 12:53:36PM +0100, Martyn Welch wrote: > >> On 23/06/11 12:45, Ralf Baechle wrote: >>> On architectures that don't define PAGE_KERNEL_NOCACHE, the Comedi driver turns >>> into tragedy: >>> >>> CC [M] drivers/staging/comedi/drivers.o >>> drivers/staging/comedi/drivers.c: In function ‘comedi_buf_alloc’: >>> drivers/staging/comedi/drivers.c:505:41: error: ‘PAGE_KERNEL_NOCACHE’ undeclared (first use in this function) >>> drivers/staging/comedi/drivers.c:505:41: note: each undeclared identifier is rep orted only once for each function it appears in >>> make[3]: *** [drivers/staging/comedi/drivers.o] Error 1 >>> >>> Restrict the driver to only those architectures that define PAGE_KERNEL_NOCACHE. >>> >>> PAGE_KERNEL_NOCACHE is a kludge - some system architectures such as SGI IP27 >>> are even uable to offer uncached operation - at least in the way an unwitting >>> driver might assume. I haven't looked in details how the driver is using >>> the area vmaped with PAGE_KERNEL_NOCACHE but maybe doing it XFS-style using >>> cached memory and the flush_kernel_vmap_range / invalidate_kernel_vmap_range >>> APIs in conjunction with the DMA API is a practical alternative. >>> >>> Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> >>> >>> drivers/staging/comedi/Kconfig | 1 + >>> 1 files changed, 1 insertions(+), 0 deletions(-) >>> >>> diff --git a/drivers/staging/comedi/Kconfig b/drivers/staging/comedi/Kconfig >>> index 1502d80..bccdc12 100644 >>> --- a/drivers/staging/comedi/Kconfig >>> +++ b/drivers/staging/comedi/Kconfig >>> @@ -2,6 +2,7 @@ config COMEDI >>> tristate "Data acquisition support (comedi)" >>> default N >>> depends on m >>> + depends on BROKEN || FRV || M32R || MN10300 || SUPERH || TILE || X86 >> >> I'm sure I got comedi to compile on a 32-bit PPC board not that long ago. Has >> something changed, or is this just not an exhaustive list? > > (Adding the PPC folks to cc.) > > A "git grep -w PAGE_KERNEL_NOCACHE arch/powerpc/" doesn't find anything so > I don't think the driver will build there. I don't have a PPC toolchain > to verify that. I can verify it fails on PPC as well: drivers/staging/comedi/drivers.c: In function 'comedi_buf_alloc': drivers/staging/comedi/drivers.c:505:37: error: 'PAGE_KERNEL_NOCACHE' undeclared (first use in this function) drivers/staging/comedi/drivers.c:505:37: note: each undeclared identifier is reported only once for each function it appears in However, we do have a #define for PAGE_KERNEL_NC. - k _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/devel
