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From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: <linux-riscv@lists.infradead.org>,
	Palmer Dabbelt <palmer@dabbelt.com>, <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: [PATCH 2/2] riscv: Add mem kernel parameter support
Date: Wed, 2 Jun 2021 16:55:17 +0800	[thread overview]
Message-ID: <20210602085517.127481-2-wangkefeng.wang@huawei.com> (raw)
In-Reply-To: <20210602085517.127481-1-wangkefeng.wang@huawei.com>

The memblock_enforce_memory_limit() could change the memblock
range, so move the dram_end assignment after it in bootmem_init(),
then support mem= cmdline.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/riscv/mm/init.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 17f2e1da2b3d..ce61510a08c0 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -127,19 +127,39 @@ void __init mem_init(void)
 	print_vm_layout();
 }
 
+/*
+ * The default maximal physical memory size is -PAGE_OFFSET,
+ * limit the memory size via mem.
+ */
+static phys_addr_t memory_limit = -PAGE_OFFSET;
+
+static int __init early_mem(char *p)
+{
+	u64 size;
+
+	if (!p)
+		return 1;
+
+	size = memparse(p, &p) & PAGE_MASK;
+	memory_limit = min_t(u64, size, memory_limit);
+
+	pr_notice("Memory limited to %lldMB\n", (u64)memory_limit >> 20);
+
+	return 0;
+}
+early_param("mem", early_mem);
+
 void __init setup_bootmem(void)
 {
 	phys_addr_t vmlinux_end = __pa_symbol(&_end);
 	phys_addr_t vmlinux_start = __pa_symbol(&_start);
-	phys_addr_t dram_end = memblock_end_of_DRAM();
 	phys_addr_t max_mapped_addr = __pa(~(ulong)0);
+	phys_addr_t dram_end;
 
 #ifdef CONFIG_XIP_KERNEL
 	vmlinux_start = __pa_symbol(&_sdata);
 #endif
-
-	/* The maximal physical memory size is -PAGE_OFFSET. */
-	memblock_enforce_memory_limit(-PAGE_OFFSET);
+	memblock_enforce_memory_limit(memory_limit);
 
 	/*
 	 * Reserve from the start of the kernel to the end of the kernel
@@ -154,6 +174,7 @@ void __init setup_bootmem(void)
 #endif
 	memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
 
+	dram_end = memblock_end_of_DRAM();
 	/*
 	 * memblock allocator is not aware of the fact that last 4K bytes of
 	 * the addressable memory can not be mapped because of IS_ERR_VALUE
-- 
2.18.0.huawei.25


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  reply	other threads:[~2021-06-02  9:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-02  8:55 [PATCH 1/2] riscv: Only initialize swiotlb when necessary Kefeng Wang
2021-06-02  8:55 ` Kefeng Wang [this message]
2021-06-11 21:18   ` [PATCH 2/2] riscv: Add mem kernel parameter support Palmer Dabbelt

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