On Wed, Jun 29, 2016 at 02:51:28PM +0200, Ard Biesheuvel wrote:

+	if (!PAGE_ALIGNED(md->phys_addr) ||
+	    !PAGE_ALIGNED(md->num_pages << EFI_PAGE_SHIFT)) {
+		/*
+		 * If the end address of this region is not aligned to page
+		 * size, the mapping is rounded up, and may end up sharing a
+		 * page frame with the next UEFI memory region. If we create
+		 * a block entry now, we may need to split it again when mapping
+		 * the next region, and support for that is going to be removed
+		 * from the MMU routines. So avoid block mappings altogether in
+		 * that case.
+		 */
+		allow_block_mappings = false;
+	}

How common is it for large areas to have unaligned start/end? I wonder
whether it's worth implementing my approach to look ahead and explicitly
check the overlap with the next section instead of disabling block
mappings altogether for this region.

-- 
Catalin