diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1d1d53f85ddd7..5529fa82700ba 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2237,6 +2237,15 @@
 			The memory region may be marked as e820 type 12 (0xc)
 			and is NVDIMM or ADR memory.
 
+	memmap=<size>%<offset>-<oldtype>+<newtype>
+			[KNL,ACPI] Convert memory within the specified region
+			from <oldtype> to <newtype>. If "-<oldtype>" is left
+			out, the whole region will be marked as <newtype>,
+			even if previously unavailable. If "+<newtype>" is left
+			out, matching memory will be removed. Types are
+			specified as e820 types, e.g., 1 = RAM, 2 = reserved,
+			3 = ACPI, 12 = PRAM.
+
 	memory_corruption_check=0/1 [X86]
 			Some BIOSes seem to corrupt the first 64k of
 			memory when doing things like suspend/resume.
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 71c11ad5643e8..6a2cb1442e05a 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -924,6 +924,24 @@ static int __init parse_memmap_one(char *p)
 	} else if (*p == '!') {
 		start_at = memparse(p+1, &p);
 		e820__range_add(start_at, mem_size, E820_TYPE_PRAM);
+	} else if (*p == '%') {
+		enum e820_type from = 0, to = 0;
+
+		start_at = memparse(p + 1, &p);
+		if (*p == '-')
+			from = simple_strtoull(p + 1, &p, 0);
+		if (*p == '+')
+			to = simple_strtoull(p + 1, &p, 0);
+		if (*p != '\0')
+			return -EINVAL;
+		if (from && to)
+			e820__range_update(start_at, mem_size, from, to);
+		else if (to)
+			e820__range_add(start_at, mem_size, to);
+		else if (from)
+			e820__range_remove(start_at, mem_size, from, 1);
+		else
+			e820__range_remove(start_at, mem_size, 0, 0);
 	} else {
 		e820__range_remove(mem_size, ULLONG_MAX - mem_size, E820_TYPE_RAM, 1);
 	}