1 files changed, 81 insertions, 0 deletions
diff --git a/roms/ipxe/src/core/memblock.c b/roms/ipxe/src/core/memblock.c
new file mode 100644
index 00000000..1fd89b87
--- /dev/null
+++ b/roms/ipxe/src/core/memblock.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Largest memory block
+ *
+ */
+
+#include <stdint.h>
+#include <ipxe/uaccess.h>
+#include <ipxe/io.h>
+#include <ipxe/memblock.h>
+
+/**
+ * Find largest usable memory region
+ *
+ * @ret start		Start of region
+ * @ret len		Length of region
+ */
+size_t largest_memblock ( userptr_t *start ) {
+	struct memory_map memmap;
+	struct memory_region *region;
+	physaddr_t max = ~( ( physaddr_t ) 0 );
+	physaddr_t region_start;
+	physaddr_t region_end;
+	size_t region_len;
+	unsigned int i;
+	size_t len = 0;
+
+	/* Avoid returning uninitialised data on error */
+	*start = UNULL;
+
+	/* Scan through all memory regions */
+	get_memmap ( &memmap );
+	for ( i = 0 ; i < memmap.count ; i++ ) {
+		region = &memmap.regions[i];
+		DBG ( "Considering [%llx,%llx)\n", region->start, region->end );
+
+		/* Truncate block to maximum physical address */
+		if ( region->start > max ) {
+			DBG ( "...starts after maximum address %lx\n", max );
+			continue;
+		}
+		region_start = region->start;
+		if ( region->end > max ) {
+			DBG ( "...end truncated to maximum address %lx\n", max);
+			region_end = 0; /* =max, given the wraparound */
+		} else {
+			region_end = region->end;
+		}
+		region_len = ( region_end - region_start );
+
+		/* Use largest block */
+		if ( region_len > len ) {
+			DBG ( "...new best block found\n" );
+			*start = phys_to_user ( region_start );
+			len = region_len;
+		}
+	}
+
+	return len;
+}