Re: Latest -git ioremap error

From: Ingo Molnar
Date: Sun Feb 03 2008 - 16:34:34 EST



* Kevin Winchester <kjwinchester@xxxxxxxxx> wrote:

> > x86: fix ioremap RAM check
> >
> > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>
> Lucky first try - reverting this commit fixes the problem for me. Any
> ideas?

Could you check the patch below - does that too fix the problem for you?

Ingo

----------------->
Subject: x86: relax RAM check in ioremap()
From: Ingo Molnar <mingo@xxxxxxx>

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 266b9f8727976769e2ed2dad77ac9295f37e321e
> Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> 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@xxxxxxxxx>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/x86/mm/ioremap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

Index: linux-x86.q/arch/x86/mm/ioremap.c
===================================================================
--- linux-x86.q.orig/arch/x86/mm/ioremap.c
+++ linux-x86.q/arch/x86/mm/ioremap.c
@@ -116,7 +116,7 @@ static void __iomem *__ioremap(unsigned
{
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 +133,9 @@ static void __iomem *__ioremap(unsigned
/*
* 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 (pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))
return NULL;
}

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