On Fri, Aug 01, 2014 at 06:04:11PM +0100, Robert Richter wrote: > Mark, Hi Robert, > On 31.07.14 12:33:01, Mark Rutland wrote: > > On Thu, Jul 31, 2014 at 12:12:33PM +0100, Ganapatrao Kulkarni wrote: > > > We mark RAM used by ATF as secure-RAM, however we don't support > > > secure/non-secure address aliasing. > > > i.e, a DRAM address that can be referenced from both a secure PA and a > > > non-secure PA is not allowed. > > > > What exactly do you mean by "not allowed"? > > It actually means "not possible" since secure and non-secure memory is > kept in separate address ranges. I understand that the two are separate physical address spaces, but Ganapatrao's reply was somewhat ambiguous and it wasn't clear to me that the memory was actually marked as secure. > > If Linux maps that memory, what happens? > > > > What if Linux tried to read or write to it? > > > > If Linux should not map that memory, it should not be described in the > > memory map to begin with. > > Linux never will see secure-RAM. Firmware must be sure to report the > correct non-secure memory ranges to the OS (e.g. unsecure mem size = > total size - secure mem size). Ok, that's what I had hoped for and that makes sense. The issue was that the memory node contained an address range that was supposedly secure-only (which Linux could attempt to map), which was 'protected' with a /memreserve/ (which does not stop it from being mapped). Given they are unnecessary (unless you want to bypass EFI for some reason) they can be dropped. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
