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This patch covers parsing of the following two formats for 'memmap' parameter values: - nn[KMG]@ss[KMG] - nn[KMG]$ss[KMG] ([KMG] =3D K M or G (kilo, mega, giga)) These two allowed formats for parameter value are already documented in file kernel-parameters.txt in Documentation/admin-guide folder. Some architectures already support them, but Mips did not prior to this patch. Excerpt from Documentation/admin-guide/kernel-parameters.txt: memmap=3Dnn[KMG]@ss[KMG] [KNL] Force usage of a specific region of memory. Region of memory to be used is from ss to ss+nn. memmap=3Dnn[KMG]$ss[KMG] Mark specific memory as reserved. Region of memory to be reserved is from ss to ss+nn. Example: Exclude memory from 0x18690000-0x1869ffff memmap=3D64K$0x18690000 or memmap=3D0x10000$0x18690000 There is no need to update this documentation file with respect to this patch. Signed-off-by: Yunhui Cui --- arch/riscv/mm/init.c | 50 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index e3405e4b99af..7be7ec3092ad 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -208,6 +208,56 @@ static int __init early_mem(char *p) } early_param("mem", early_mem); =20 +static void __init parse_memmap_one(char *p) +{ + char *oldp; + unsigned long start_at, mem_size; + + if (!p) + return; + + oldp =3D p; + mem_size =3D memparse(p, &p); + if (p =3D=3D oldp) + return; + + switch (*p) { + case '@': + start_at =3D memparse(p + 1, &p); + memblock_add(start_at, mem_size); + break; + + case '$': + start_at =3D memparse(p + 1, &p); + memblock_reserve(start_at, mem_size); + break; + + case 0: + memblock_reserve(mem_size, -mem_size); + break; + + default: + pr_warn("Unrecognized memmap syntax: %s\n", p); + break; + } +} + +static int __init parse_memmap_opt(char *str) +{ + while (str) { + char *k =3D strchr(str, ','); + + if (k) + *k++ =3D 0; + + parse_memmap_one(str); + str =3D k; + } + + return 0; +} +early_param("memmap", parse_memmap_opt); + static void __init setup_bootmem(void) { phys_addr_t vmlinux_end =3D __pa_symbol(&_end); --=20 2.20.1