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x86: relax RAM check in ioremap() 

Kevin Winchester reported the loss of direct rendering, due to:

[    0.588184] agpgart: Detected AGP bridge 0
[    0.588184] agpgart: unable to get memory for graphics translation table.
[    0.588184] agpgart: agp_backend_initialize() failed.
[    0.588207] agpgart-amd64: probe of 0000:00:00.0 failed with error -12

and bisected it down to:

  commit 266b9f8727
  Author: Thomas Gleixner <tglx@linutronix.de>
  Date:   Wed Jan 30 13:34:06 2008 +0100

      x86: fix ioremap RAM check

this check was too strict and caused an ioremap() failure.

the problem is due to the somewhat unclean way of how the GART code
reserves a memory range for its aperture, and how it utilizes it
later on.

Allow RAM pages to be ioremap()-ed too, as long as they are reserved.

Bisected-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Kevin Winchester <kjwinchester@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2008-02-04 16:47:54 +01:00
parent 9135f1901e
commit 38cb47ba01
1 changed files with 5 additions and 4 deletions
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9
arch/x86/mm/ioremap.c
View File

@ -116,7 +116,7 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
{
void __iomem *addr;
struct vm_struct *area;
unsigned long offset, last_addr;
unsigned long pfn, offset, last_addr;
pgprot_t prot;
/* Don't allow wraparound or zero size */
@ -133,9 +133,10 @@ static void __iomem *__ioremap(unsigned long phys_addr, unsigned long size,
/*
* Don't allow anybody to remap normal RAM that we're using..
*/
for (offset = phys_addr >> PAGE_SHIFT; offset < max_pfn_mapped &&
(offset << PAGE_SHIFT) < last_addr; offset++) {
if (page_is_ram(offset))
for (pfn = phys_addr >> PAGE_SHIFT; pfn < max_pfn_mapped &&
(pfn << PAGE_SHIFT) < last_addr; pfn++) {
if (page_is_ram(pfn) && pfn_valid(pfn) &&
!PageReserved(pfn_to_page(pfn)))
return NULL;
}