Hi Ralf, On Thu, 23 Jun 2011 12:45:37 +0100 Ralf Baechle <[email protected]> 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 <[email protected]>
Since Greg is on vacation, I will add this patch to my fixes tree in linux-next until a better fix comes along (if there is one). -- Cheers, Stephen Rothwell [email protected] http://www.canb.auug.org.au/~sfr/
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