1 files changed, 144 insertions, 0 deletions
diff --git a/src/core/memmap.c b/src/core/memmap.c
new file mode 100644
index 000000000..4a96055e6
--- /dev/null
+++ b/src/core/memmap.c
@@ -0,0 +1,144 @@
+/*
+ * Copyright (C) 2025 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.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <assert.h>
+#include <ipxe/io.h>
+#include <ipxe/memmap.h>
+
+/** @file
+ *
+ * System memory map
+ *
+ */
+
+/**
+ * Update memory region descriptor
+ *
+ * @v region		Memory region of interest to be updated
+ * @v start		Start address of known region
+ * @v size		Size of known region
+ * @v flags		Flags for known region
+ * @v name		Name of known region (for debugging)
+ *
+ * Update a memory region descriptor based on a known existent region.
+ */
+void memmap_update ( struct memmap_region *region, uint64_t start,
+		     uint64_t size, unsigned int flags, const char *name ) {
+	uint64_t max;
+
+	/* Sanity check */
+	assert ( region->max >= region->min );
+
+	/* Ignore empty regions */
+	if ( ! size )
+		return;
+
+	/* Calculate max addresses (and truncate if necessary) */
+	max = ( start + size - 1 );
+	if ( max < start ) {
+		max = ~( ( uint64_t ) 0 );
+		DBGC ( region, "MEMMAP [%#08llx,%#08llx] %s truncated "
+		       "(invalid size %#08llx)\n",
+		       ( ( unsigned long long ) start ),
+		       ( ( unsigned long long ) max ), name,
+		       ( ( unsigned long long ) size ) );
+	}
+
+	/* Ignore regions entirely below the region of interest */
+	if ( max < region->min )
+		return;
+
+	/* Ignore regions entirely above the region of interest */
+	if ( start > region->max )
+		return;
+
+	/* Update region of interest as applicable */
+	if ( start <= region->min ) {
+
+		/* Record this region as covering the region of interest */
+		region->flags |= flags;
+		if ( name )
+			region->name = name;
+
+		/* Update max address if no closer boundary exists */
+		if ( max < region->max )
+			region->max = max;
+
+	} else if ( start < region->max ) {
+
+		/* Update max address if no closer boundary exists */
+		region->max = ( start - 1 );
+	}
+
+	/* Sanity check */
+	assert ( region->max >= region->min );
+}
+
+/**
+ * Update memory region descriptor based on all in-use memory regions
+ *
+ * @v region		Memory region of interest to be updated
+ */
+void memmap_update_used ( struct memmap_region *region ) {
+	struct used_region *used;
+
+	/* Update descriptor to hide all in-use regions */
+	for_each_table_entry ( used, USED_REGIONS ) {
+		memmap_update ( region, used->start, used->size,
+				MEMMAP_FL_USED, used->name );
+	}
+}
+
+/**
+ * Find largest usable memory region
+ *
+ * @v start		Start address to fill in
+ * @ret len		Length of region
+ */
+size_t memmap_largest ( physaddr_t *start ) {
+	struct memmap_region region;
+	size_t largest;
+	size_t size;
+
+	/* Find largest usable region */
+	DBGC ( &region, "MEMMAP finding largest usable region\n" );
+	*start = 0;
+	largest = 0;
+	for_each_memmap ( &region, 1 ) {
+		DBGC_MEMMAP ( &region, &region );
+		if ( ! memmap_is_usable ( &region ) )
+			continue;
+		size = memmap_size ( &region );
+		if ( size > largest ) {
+			DBGC ( &region, "...new largest region found\n" );
+			largest = size;
+			*start = region.min;
+		}
+	}
+	return largest;
+}
+
+PROVIDE_MEMMAP_INLINE ( null, memmap_describe );
+PROVIDE_MEMMAP_INLINE ( null, memmap_sync );