On Thu, Jun 23, 2011 at 12:53:36PM +0100, Martyn Welch wrote:
On 23/06/11 12:45, Ralf Baechle wrote:
quoted
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 <redacted>
drivers/staging/comedi/Kconfig | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
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.
Ralf
On Thu, Jun 23, 2011 at 12:53:36PM +0100, Martyn Welch wrote:
quoted
On 23/06/11 12:45, Ralf Baechle wrote:
quoted
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 <redacted>
drivers/staging/comedi/Kconfig | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
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.
Ah, just found the tree looks like I had a little patch to make it seemingly
work, though it will make it "not work" for most other archs at a guess (it
may not even be right on PPC):
@@ -505,7 +505,7 @@ int comedi_buf_alloc(struct comedi_device *dev, struct
comedi_subdevice *s,
}
if (i == n_pages) {
async->prealloc_buf =
- vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NOCACHE);
+ vmap(pages, n_pages, VM_MAP, PAGE_KERNEL_NC);
}
vfree(pages);
(Sorry for the wrapping)
--
Martyn Welch (Principal Software Engineer) | Registered in England and
GE Intelligent Platforms | Wales (3828642) at 100
T +44(0)127322748 | Barbirolli Square, Manchester,
E martyn.welch@ge.com | M2 3AB VAT:GB 927559189
From: Kumar Gala <hidden> Date: 2011-06-23 12:24:03
On Jun 23, 2011, at 7:02 AM, Ralf Baechle wrote:
On Thu, Jun 23, 2011 at 12:53:36PM +0100, Martyn Welch wrote:
=20
quoted
On 23/06/11 12:45, Ralf Baechle wrote:
quoted
On architectures that don't define PAGE_KERNEL_NOCACHE, the Comedi =
driver turns
quoted
quoted
into tragedy:
=20
CC [M] drivers/staging/comedi/drivers.o
drivers/staging/comedi/drivers.c: In function =91comedi_buf_alloc=92:
drivers/staging/comedi/drivers.c:505:41: error: =
=91PAGE_KERNEL_NOCACHE=92 undeclared (first use in this function)
quoted
quoted
drivers/staging/comedi/drivers.c:505:41: note: each undeclared =
identifier is rep orted only once for each function it appears in
quoted
quoted
make[3]: *** [drivers/staging/comedi/drivers.o] Error 1
=20
Restrict the driver to only those architectures that define =
PAGE_KERNEL_NOCACHE.
quoted
quoted
=20
PAGE_KERNEL_NOCACHE is a kludge - some system architectures such as =
SGI IP27
quoted
quoted
are even uable to offer uncached operation - at least in the way an =
unwitting
quoted
quoted
driver might assume. I haven't looked in details how the driver is =
using
quoted
quoted
the area vmaped with PAGE_KERNEL_NOCACHE but maybe doing it =
XFS-style using
quoted
quoted
cached memory and the flush_kernel_vmap_range / =
invalidate_kernel_vmap_range
quoted
quoted
APIs in conjunction with the DMA API is a practical alternative.
=20
Signed-off-by: Ralf Baechle <redacted>
=20
drivers/staging/comedi/Kconfig | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
=20
tristate "Data acquisition support (comedi)"
default N
depends on m
+ depends on BROKEN || FRV || M32R || MN10300 || SUPERH || TILE || =
X86
quoted
=20
I'm sure I got comedi to compile on a 32-bit PPC board not that long =
ago. Has
quoted
something changed, or is this just not an exhaustive list?
=20
(Adding the PPC folks to cc.)
=20
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=
From: Benjamin Herrenschmidt <benh@kernel.crashing.org> Date: 2011-06-23 22:02:39
On Thu, 2011-06-23 at 13:02 +0100, Ralf Baechle wrote:
On Thu, Jun 23, 2011 at 12:53:36PM +0100, Martyn Welch wrote:
quoted
On 23/06/11 12:45, Ralf Baechle wrote:
quoted
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 <redacted>
drivers/staging/comedi/Kconfig | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
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?
It went away. There's a proper API (pgprot_noncached), but it depends
what this is used for and it's likely to be broken anyways... what is
that driver trying to map non-cached ?
Cheers,
Ben.
(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.
Ralf
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