On 19 Mar 2005, at 10:56, Christian Limpach wrote:
For this specific case there may be another resolution but could
you please, please look at marking the missing pages PG_reserved
and not hacking phys_to_virt.
At this point anything short of explicitly introducing an intermediate
step say virt_to_
On Sat, Mar 19, 2005 at 03:07:18AM -0700, Eric W. Biederman wrote:
> For this specific case there may be another resolution but could
> you please, please look at marking the missing pages PG_reserved
> and not hacking phys_to_virt.
>
> At this point anything short of explicitly introducing an int
Keir Fraser <[EMAIL PROTECTED]> writes:
> > > now, the patch lines that poke into the GATT I guess stay as they are.
> > > We can maintain an out-of-tree patch for Xen, or perhaps if
> > > virt_to_phys() is not used very much we can override its definition.
> >
> > It sounds like xen is trying
On 18 Mar 2005, at 00:16, Paul Mackerras wrote:
That sounds like a good way to make AGP accesses slower. :)
Seriously, given that AGP is a technology that is being superseded by
PCI Express, I think it's reasonable to look at the range of current
implementations to see what we have to cope with. S
On Fri, 18 Mar 2005, Paul Mackerras wrote:
> However, the idea of having phys_to_agp/agp_to_phys (or
> virt_to_agp/agp_to_virt) sounds like it wouldn't be too much effort, if
> it would help Xen.
It would be absolutely trivial. On most architectures you would have:
#define virt_to_agp virt_t
Alan Cox writes:
> On Iau, 2005-03-17 at 09:34, Paul Mackerras wrote:
> > This code needs real physical addresses, which are not the same things
> > as bus addresses.
>
> Not always. The code needs platform specific goodies. We've only never
> been burned so far because there isn't a box with a
On Iau, 2005-03-17 at 09:34, Paul Mackerras wrote:
> This code needs real physical addresses, which are not the same things
> as bus addresses.
Not always. The code needs platform specific goodies. We've only never
been burned so far because there isn't a box with an IOMMU and AGPGART
where one
> > So: I would very much like you to take the patches I made to generic.c
> > that replace __get_free_pages() calls with dma_alloc_coherent(). For
>
> This is also wrong - the base address of the GATT is a physical
> address not a bus address. This change will break agpgart on ppc64
> systems
Keir Fraser writes:
> Yes, Xen will break w/o them, because physical addresses are an
> illusory trick that the guest OS plays on itself to give itself the
> impression of a contiguous memory map. We use _to_machine and _to_bus
> macros to get 'real' physical addresses.
This code needs real ph
On 16 Mar 2005, at 22:06, Jesse Barnes wrote:
The distinction is that physical addresses are what are used to access
physical memory, whereas bus addresses are what appears on some
external bus (usually PCI). The GATT sits between an external (AGP)
bus and memory, so while the GATT is indexed usin
On Thu, 17 Mar 2005, Christoph Hellwig wrote:
> On Wed, Mar 16, 2005 at 06:55:13PM -0500, Rik van Riel wrote:
> > Thing is, the rest of the kernel uses virt_to_phys for
> > two different things. Only one of them has to do with
> > the real physical address, the other is about getting
> > the page
On Wed, Mar 16, 2005 at 06:55:13PM -0500, Rik van Riel wrote:
> Thing is, the rest of the kernel uses virt_to_phys for
> two different things. Only one of them has to do with
> the real physical address, the other is about getting
> the page frame number.
The latter usage has been converted to pa
On Thu, 17 Mar 2005, Paul Mackerras wrote:
> > Under Xen, however, the two are different - and the
> > AGPGART really needs to have the physical address ;)
>
> If Xen is letting the kernel program the GART, you just lost any
> memory isolation between partitions you might have been trying to
> en
Paul Mackerras wrote:
Rik van Riel writes:
Thing is, the rest of the kernel uses virt_to_phys for
two different things. Only one of them has to do with
the real physical address, the other is about getting
the page frame number.
So fix the places that are using virt_to_phys to get the page
Rik van Riel writes:
> Thing is, the rest of the kernel uses virt_to_phys for
> two different things. Only one of them has to do with
> the real physical address, the other is about getting
> the page frame number.
So fix the places that are using virt_to_phys to get the page frame
number to use
On Wed, 16 Mar 2005, Jesse Barnes wrote:
> Thanks for the explanation Paul, now the code actually makes sense.
> Converting to the DMA mapping API doesn't make sense at all in this context
> then, since we're basically programming the GATT (an IOMMU type table) with
> physical addresses. Ken,
On Wednesday, March 16, 2005 1:24 pm, Paul Mackerras wrote:
> Keir Fraser writes:
> > This patch cleans up AGP driver treatment of bus/device memory. Every
> > use of virt_to_phys/phys_to_virt should properly be converting between
> > virtual and bus addresses: this distinction really matters for t
Keir Fraser writes:
> This patch cleans up AGP driver treatment of bus/device memory. Every
> use of virt_to_phys/phys_to_virt should properly be converting between
> virtual and bus addresses: this distinction really matters for the Xen
> hypervisor.
I think you are misunderstanding the distinct
On 16 Mar 2005, at 19:06, Christoph Hellwig wrote:
The AGP driver is only configurable for ppc32, alpha, x86, x86_64 and
ia64, all of which have virt_to_bus.
and ppc64 now, which doesn't.
Sounds like the new DMA-mapping interface is the way to go then.
-- Keir
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On Wed, Mar 16, 2005 at 06:35:28PM +, Keir Fraser wrote:
>
> On 16 Mar 2005, at 18:10, Christoph Hellwig wrote:
>
> >On Wed, Mar 16, 2005 at 10:01:07AM -0500, Rik van Riel wrote:
> >>In the case of AGP, the AGPGART effectively _is_ the
> >>IOMMU. Calculating the addresses right for programmi
On 16 Mar 2005, at 18:42, Jesse Barnes wrote:
The AGP driver is only configurable for ppc32, alpha, x86, x86_64 and
ia64, all of which have virt_to_bus.
Yeah, but that doesn't mean it makes sense on all those platforms. The
biggest problem with virt_to_bus (well, depending on who you talk to)
is
On Wednesday, March 16, 2005 10:35 am, Keir Fraser wrote:
> On 16 Mar 2005, at 18:10, Christoph Hellwig wrote:
> > On Wed, Mar 16, 2005 at 10:01:07AM -0500, Rik van Riel wrote:
> >> In the case of AGP, the AGPGART effectively _is_ the
> >> IOMMU. Calculating the addresses right for programming
> >
On 16 Mar 2005, at 18:10, Christoph Hellwig wrote:
On Wed, Mar 16, 2005 at 10:01:07AM -0500, Rik van Riel wrote:
In the case of AGP, the AGPGART effectively _is_ the
IOMMU. Calculating the addresses right for programming
the AGPGART is probably worth fixing.
Well, it's a half-assed one. And some
On Wed, Mar 16, 2005 at 10:01:07AM -0500, Rik van Riel wrote:
> In the case of AGP, the AGPGART effectively _is_ the
> IOMMU. Calculating the addresses right for programming
> the AGPGART is probably worth fixing.
Well, it's a half-assed one. And some systems have a real one.
But the real probl
On Wednesday, March 16, 2005 3:48 am, Keir Fraser wrote:
> This patch cleans up AGP driver treatment of bus/device memory. Every
> use of virt_to_phys/phys_to_virt should properly be converting between
> virtual and bus addresses: this distinction really matters for the Xen
> hypervisor.
>
> Furthe
On Mer, 2005-03-16 at 14:31, Christoph Hellwig wrote:
> It's bogus either way. You must never use virt_to_phys or virt_to_bus
> for bus address. For systems with an IOMMU there's no 1:1 mapping.
The AGPGART _is_ the IOMMU.
Alan
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On Wed, 16 Mar 2005, Christoph Hellwig wrote:
> On Wed, Mar 16, 2005 at 11:48:29AM +, Keir Fraser wrote:
> > This patch cleans up AGP driver treatment of bus/device memory. Every
> > use of virt_to_phys/phys_to_virt should properly be converting between
> > virtual and bus addresses: this disti
> On Wed, Mar 16, 2005 at 11:48:29AM +, Keir Fraser wrote:
> > This patch cleans up AGP driver treatment of bus/device memory. Every
> > use of virt_to_phys/phys_to_virt should properly be converting between
> > virtual and bus addresses: this distinction really matters for the Xen
> > hypervis
On Wed, Mar 16, 2005 at 11:48:29AM +, Keir Fraser wrote:
> This patch cleans up AGP driver treatment of bus/device memory. Every
> use of virt_to_phys/phys_to_virt should properly be converting between
> virtual and bus addresses: this distinction really matters for the Xen
> hypervisor.
It's
This patch cleans up AGP driver treatment of bus/device memory. Every
use of virt_to_phys/phys_to_virt should properly be converting between
virtual and bus addresses: this distinction really matters for the Xen
hypervisor.
Furthermore, when allocating the GATT, it is necessary to use
dma_alloc_co
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