Staging: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE
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@linux-mips.org> Reported-by: David Miller <davem@davemloft.net> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Martyn Welch <martyn.welch@ge.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -2,6 +2,7 @@ config COMEDI
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tristate "Data acquisition support (comedi)"
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default N
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depends on m
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depends on BROKEN || FRV || M32R || MN10300 || SUPERH || TILE || X86
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---help---
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Enable support a wide range of data acquisition devices
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for Linux.
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