Re: ioremap_nocache and mem= parameter with k 2.6.18

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[email protected] wrote:
Hi,
I'm using a driver for a framegrabber device that needs to alloc a
huge buffer of ram for dma transfers....
So it works:
1) Having 2GB of ram installed, boot the kernel with mem=1024M
parameter
2) remap the unmapped memory above first GB using ioremap_nocache
function, using PAGE_ALIGN().

This works fine with kernel 2.6.9 but it doesn't with newer ones
2.6.18, 2.6.20, 2.6.22.
With newer kernel ioremap returns 0.
It seems like memory above 1G has been marked reserved, IMHO.

What changes in the mm?
I'm not the driver's developer, but I'd like to understand and
possibly find a workaround...
It doesn't make sense to use ioremap_nocache on RAM. It's only meant for
mapping MMIO memory regions on a device.
--
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from [email protected]
Home Page: http://www.roberthancock.com/

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