Messages in this thread | | | Date | Thu, 11 Oct 2007 22:18:15 -0600 | From | Robert Hancock <> | Subject | Re: ioremap_nocache and mem= parameter with k 2.6.18 |
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mirco_cremasco@hotmail.com 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 hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/
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