* Re: [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE
2011-06-23 12:02 ` [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE Ralf Baechle
@ 2011-06-23 12:10 ` Kumar Gala
2011-06-23 12:13 ` Martyn Welch
2011-06-23 22:01 ` Benjamin Herrenschmidt
2 siblings, 0 replies; 4+ messages in thread
From: Kumar Gala @ 2011-06-23 12:10 UTC (permalink / raw)
To: Ralf Baechle
Cc: devel, David Howells, linux-m32r, Paul Mundt, linux-sh,
Greg Kroah-Hartman, linux-kernel, Chris Metcalf, Martyn Welch,
linux-am33-list, Paul Mackerras, linux-m32r-ja, H. Peter Anvin,
Thomas Gleixner, linux-arch, linuxppc-dev, Ingo Molnar, x86
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
>> On 23/06/11 12:45, Ralf Baechle wrote:
>>> On architectures that don't define PAGE_KERNEL_NOCACHE, the Comedi =
driver turns
>>> 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)
>>> 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
>>>=20
>>> Restrict the driver to only those architectures that define =
PAGE_KERNEL_NOCACHE.
>>>=20
>>> 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.
>>>=20
>>> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
>>>=20
>>> drivers/staging/comedi/Kconfig | 1 +
>>> 1 files changed, 1 insertions(+), 0 deletions(-)
>>>=20
>>> 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
>>=20
>> 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?
>=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=
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE
2011-06-23 12:02 ` [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE Ralf Baechle
2011-06-23 12:10 ` Kumar Gala
@ 2011-06-23 12:13 ` Martyn Welch
2011-06-23 22:01 ` Benjamin Herrenschmidt
2 siblings, 0 replies; 4+ messages in thread
From: Martyn Welch @ 2011-06-23 12:13 UTC (permalink / raw)
To: Ralf Baechle
Cc: devel, linux-m32r-ja, linux-m32r, Paul Mundt, linux-sh,
Greg Kroah-Hartman, linux-kernel, Chris Metcalf, David Howells,
linux-am33-list, Paul Mackerras, H. Peter Anvin, Thomas Gleixner,
linux-arch, linuxppc-dev, Ingo Molnar, x86
On 23/06/11 13:02, 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@linux-mips.org>
>>>
>>> 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.
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):
diff --git a/drivers/staging/comedi/drivers.c b/drivers/staging/comedi/drivers.c
index 44d6b62..263ad3d 100644
--- a/drivers/staging/comedi/drivers.c
+++ b/drivers/staging/comedi/drivers.c
@@ -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
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE
2011-06-23 12:02 ` [PATCH] STAGING: Comedi: Build only on arches providing PAGE_KERNEL_NOCACHE Ralf Baechle
2011-06-23 12:10 ` Kumar Gala
2011-06-23 12:13 ` Martyn Welch
@ 2011-06-23 22:01 ` Benjamin Herrenschmidt
2 siblings, 0 replies; 4+ messages in thread
From: Benjamin Herrenschmidt @ 2011-06-23 22:01 UTC (permalink / raw)
To: Ralf Baechle
Cc: devel, David Howells, linux-m32r, Paul Mundt, linux-sh,
Greg Kroah-Hartman, linux-kernel, Chris Metcalf, Martyn Welch,
linux-am33-list, Paul Mackerras, linux-m32r-ja, H. Peter Anvin,
Thomas Gleixner, linux-arch, linuxppc-dev, Ingo Molnar, x86
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:
>
> > 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@linux-mips.org>
> > >
> > > 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?
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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^ permalink raw reply [flat|nested] 4+ messages in thread