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Subject[PATCH v2 1/3] riscv: Add support for mem=
Date
From: Jan Kiszka <jan.kiszka@siemens.com>

This sets a memory limit provided via mem= on the command line,
analogously to many other architectures.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
arch/riscv/mm/init.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 965a8cf4829c..aec39a56d6cf 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -118,6 +118,23 @@ static void __init setup_initrd(void)
}
#endif /* CONFIG_BLK_DEV_INITRD */

+static phys_addr_t memory_limit = PHYS_ADDR_MAX;
+
+/*
+ * Limit the memory size that was specified via FDT.
+ */
+static int __init early_mem(char *p)
+{
+ if (!p)
+ return 1;
+
+ memory_limit = memparse(p, &p) & PAGE_MASK;
+ pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);
+
+ return 0;
+}
+early_param("mem", early_mem);
+
static phys_addr_t dtb_early_pa __initdata;

void __init setup_bootmem(void)
@@ -127,6 +144,8 @@ void __init setup_bootmem(void)
phys_addr_t vmlinux_end = __pa_symbol(&_end);
phys_addr_t vmlinux_start = __pa_symbol(&_start);

+ memblock_enforce_memory_limit(memory_limit);
+
/* Find the memory region containing the kernel */
for_each_memblock(memory, reg) {
phys_addr_t end = reg->base + reg->size;
--
2.16.4
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