On Sat, Jun 29, 2013 at 12:29:55PM -0700, Yinghai Lu wrote: > On Sat, Jun 29, 2013 at 10:57 AM, Tejun Heo <tj@xxxxxxxxxx> wrote: > > ( Expanding cc list, original thread is at > > http://thread.gmane.org/gmane.linux.kernel/1518046 ) > > > > Hello, > > > > On Sat, Jun 29, 2013 at 06:21:24PM +0100, Russell King - ARM Linux wrote: > >> Unfortunately, that has not been true on ARM - it's very common for > >> there to be an offset on physical memory, sometimes of the order of > >> 3GB or more. This is because on reset, ARMs start executing the code > >> at physical address zero, which therefore can't be RAM - and there's > >> a desire to avoid complex switching games in hardware to temporarily > >> map ROM there instead of RAM. > >> > >> On these SoCs which Santosh is working on, the main physical memory > >> mapping is above 4GB, with just a small alias below 4GB to allow the > >> system to boot without the MMU being on, as they may have more than > >> 4GB of RAM. As I understand it, the small alias below 4GB is not > >> suitable for use as a "lowmem" mapping. > > is that 32bit ARM or 64bit ARM? Only 32-bit has LPAE. Such things don't make sense on 64-bit CPUs. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
