Re: [PATCH v2] RISC-V: cmdline: Add support for 'memmap' parameter
From: Palmer Dabbelt
Date: Sat Sep 14 2024 - 04:21:33 EST
On Mon, 22 Jul 2024 14:13:14 PDT (-0700), punit.agrawal@xxxxxxxxxxxxx wrote:
Hi Palmer,
Charlie Jenkins <charlie@xxxxxxxxxxxx> writes:
On Mon, Jun 24, 2024 at 08:37:39PM +0800, Yunhui Cui wrote:
Add parsing of 'memmap' to use or reserve a specific region of memory.
Implement the following memmap variants:
- memmap=nn[KMG]@ss[KMG]: force usage of a specific region of memory;
- memmap=nn[KMG]$ss[KMG]: mark specified memory as reserved;
Signed-off-by: Yunhui Cui <cuiyunhui@xxxxxxxxxxxxx>
---
arch/riscv/mm/init.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index e3405e4b99af..8e1d93ae5cb2 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -208,6 +208,52 @@ static int __init early_mem(char *p)
}
early_param("mem", early_mem);
+static void __init parse_memmap_one(char *p)
+{
+ char *oldp;
+ unsigned long start_at, mem_size;
+
+ if (!p)
+ return;
+
+ oldp = p;
+ mem_size = memparse(p, &p);
+ if (p == oldp)
+ return;
+
+ switch (*p) {
+ case '@':
+ start_at = memparse(p + 1, &p);
+ memblock_add(start_at, mem_size);
+ break;
+
+ case '$':
+ start_at = memparse(p + 1, &p);
+ memblock_reserve(start_at, 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 = strchr(str, ',');
+
+ if (k)
+ *k++ = 0;
+
+ parse_memmap_one(str);
+ str = k;
+ }
+
+ return 0;
+}
+early_param("memmap", parse_memmap_opt);
+
static void __init setup_bootmem(void)
{
phys_addr_t vmlinux_end = __pa_symbol(&_end);
--
2.20.1
Reviewed-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
Another patch that looks good to get merged if there are no further
comments.
Any chance this can be picked up for this cycle?
Sorry for being slow here, but I don't understand the use case for this:
we already get the memory map from the firmware, it seems like
overriding that is just asking for issues.