Re: [PATCH 2/4] x86: ioremap: fix physical address check

From: Kenji Kaneshige
Date: Mon Jun 14 2010 - 05:03:43 EST

(2010/06/14 17:23), Kenji Kaneshige wrote:
(2010/06/14 15:38), Maciej W. Rozycki wrote:
On Mon, 14 Jun 2010, Kenji Kaneshige wrote:

- Architectural limit of physical address in x86 32-bit mode is 40-bit
(depnds on processor version).

According to documentation I happen to have handy this limit is actually
52 bits (and space is currently available in the data structures used for
a possible future extension up to 63 bits).

Thank you for pointing it out. I misunderstood that.

Now I think I need to add additional check to see if specified
physical address can be handled by x86 ioremap(), instead of
changing phys_addr_valid(). The code would be

static void __iomem *__ioremap_caller(...)
#if defined(CONFIG_X86_32) && defined(CONFIG_X86_PAE)
if (phys_addr is higer than 36-bit) {
printk(KERN_INFO "ioremap can't map physical address %llx\n",
return NULL;

Please ignore above again. Sorry for inconvenient.
According to the comment from H. Peter Anvin, 36-bit limit is on
RAM in 32-bit mode. So this approach is wrong.

Now I guess there is a bug that doesn't handle physical address
higher than 32-bit properly somewhere...

Kenji Kaneshige

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