Re: xen and agpgart

[Gerald Britton <gbritton@doomcom.org>]

> Hmmmm.... I think the problem is people using virt_to_phys() instead
> of virt_to_bus(). I would have expected the latter to be correct
> really. I'll take a look at uses of ioremap() and ioremap_nocache()
> throughout Linux. It may be there's a simple fix that will work for all
> uses... You could try manually changing the address passed in to
> virt_to_bus() and see if you get fiurther.

Ok.  I've gone through and tweaked a little to see if I could make some
more forward progress.  I've basically done s/virt_to_page/virt_to_bus/
and have gotten the system to initialize, when X starts though, I run into
another one of those pagetable tweaking oopses (below).  The code which
is executing here is pretty straightforward:

#define map_page_into_agp(page) change_page_attr(page, 1, PAGE_KERNEL_NOCACHE)

void *agp_generic_alloc_page(void)
{
        struct page * page;

        page = alloc_page(GFP_KERNEL);
        if (page == NULL)
                return NULL;

        map_page_into_agp(page);

        get_page(page);
        SetPageLocked(page);
        atomic_inc(&agp_bridge->current_memory_agp);
        return page_address(page);
}

With the code blowing up inside the change_page_attr().
Oops detail below.

				-- Gerald

Linux agpgart interface v0.100 (c) Dave Jones
agpgart: Detected an Intel 855PM Chipset.
agpgart: Maximum main memory to use for agp memory: 440M
agpgart: AGP aperture is 256M @ 0xd0000000
[drm] Initialized radeon 1.11.0 20020828 on minor 0: 
ioperm not fully supported - set iopl to 3
ioperm not fully supported - ignore resource release
ioperm not fully supported - ignore resource release
agpgart: Found an AGP 2.0 compliant device at 0000:00:00.0.
agpgart: Putting AGP V2 device at 0000:00:00.0 into 1x mode
agpgart: Putting AGP V2 device at 0000:01:00.0 into 1x mode
Unable to handle kernel paging request at virtual address c0102d64
 printing eip:
c0117ff8
*pde = ma 0308b067 pa 0048b067
*pte = ma 02c02061 pa 00002061
 [<c01181c2>] __change_page_attr+0x14e/0x21e

 [<c011830c>] change_page_attr+0x7a/0x8f

 [<e110f58e>] agp_generic_alloc_page+0x3c/0x65 [agpgart]

 [<e110e7e7>] agp_allocate_memory+0x72/0xd2 [agpgart]

 [<e1179a45>] radeon_agp_allocate_memory+0x22/0x2a [radeon]

 [<e11795e3>] radeon_agp_alloc+0xb9/0x1a2 [radeon]

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<e117dc49>] radeon_ioctl+0xc9/0x13f [radeon]

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<e117db80>] radeon_ioctl+0x0/0x13f [radeon]

 [<c016366f>] sys_ioctl+0xf7/0x24c

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<c010d2d3>] syscall_call+0x7/0xb

 [<c0106434>] inflate_dynamic+0x428/0x5f5

Oops: 0003 [#1]
PREEMPT 
Modules linked in: radeon intel_agp agpgart ds yenta_socket pcmcia_core ip_tables vfat fat ehci_hcd uhci_hcd
CPU:    0
EIP:    0061:[<c0117ff8>]    Not tainted
EFLAGS: 00013202   (2.6.8.1-xen0) 
EIP is at set_pmd_pte+0xe/0x8a
eax: c0102d64   ebx: 190000e3   ecx: d66c0000   edx: d66c0000
esi: c05e4b00   edi: 191c0063   ebp: c1109c80   esp: d3565eb0
ds: 0069   es: 0069   ss: 0069
Process X (pid: 2354, threadinfo=d3564000 task=df8091e0)
Stack: c0102d64 c05e4b00 c01181c2 c0102d64 d66c0000 190000e3 d66c0000 c13cb800 
       00000000 00000000 00000000 c011830c c13cb800 00000073 c13cb800 00000000 
       00000800 00000000 e110f58e c13cb800 00000001 00000073 e00f5500 e110e7e7 
Call Trace:
 [<c01181c2>] __change_page_attr+0x14e/0x21e

 [<c011830c>] change_page_attr+0x7a/0x8f

 [<e110f58e>] agp_generic_alloc_page+0x3c/0x65 [agpgart]

 [<e110e7e7>] agp_allocate_memory+0x72/0xd2 [agpgart]

 [<e1179a45>] radeon_agp_allocate_memory+0x22/0x2a [radeon]

 [<e11795e3>] radeon_agp_alloc+0xb9/0x1a2 [radeon]

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<e117dc49>] radeon_ioctl+0xc9/0x13f [radeon]

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<e117db80>] radeon_ioctl+0x0/0x13f [radeon]

 [<c016366f>] sys_ioctl+0xf7/0x24c

 [<c0106434>] inflate_dynamic+0x428/0x5f5

 [<c010d2d3>] syscall_call+0x7/0xb

 [<c0106434>] inflate_dynamic+0x428/0x5f5

Code: 89 18 a1 40 87 3f c0 0f b6 70 01 c6 40 01 01 b8 00 e0 ff ff 



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