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Message-id: <470EF587.3000204@shaw.ca> Date: Thu, 11 Oct 2007 22:18:15 -0600 From: Robert Hancock <hancockr@...w.ca> To: mirco_cremasco@...mail.com, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: ioremap_nocache and mem= parameter with k 2.6.18 mirco_cremasco@...mail.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@...pamshaw.ca Home Page: http://www.roberthancock.com/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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