Re: [PATCH] Prevent reserving RAM in the region already reserved by BIOS

From: Mathieu Rondonneau
Date: Wed May 19 2010 - 20:01:50 EST

it' s not in ISA space.
once loading the NVIDIA driver, the warnign oops shows up.
4K starting at 0x9f800 (i.e. to 0xa007ff) overlap with the ISA space
(starting at 0xa0000).

When I don' t load the driver, no oops.
So I am assuming nvidia driver request 4K of memory, that happens to
be available in the bios area.

I think that there is a check missing somewhere to report that
available RAM buffer is already reserved (by BIOS) so we need to get
it from somewhere else.

Does it make sense?

On Wed, May 19, 2010 at 4:00 PM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 05/19/2010 03:58 PM, Mathieu Rondonneau wrote:
>> Thanks for the feedback.
>> No, I don' t see any changes in the /proc/iomem.
>> I am trying to prevent a ioremap of a 4K size on a non aligned 4K
>> address that is below the ISA_START_ADDRESS.
>> The problem generates a oops about overlapping.
>> I have a fix which instruct to not to do any re-map if the section
>> name is "reserved".
>> Which is not really clean.
>> I am looking for a clean way to tell the ioremap function to not remap
>> bios reserved memory.
>> That' s why I thought the e820 would be a good start.
>> I will continue looking into this. It does not crash the systems. A
>> warning generates the oops.
> Why are you mapping a fixed-address in ISA space to begin with?
> Requests to a fixed address (as opposed to dynamic allocation) have to
> be granted even in reserved space -- after all, that's what the address
> might be reserved for!
>        -hpa
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at