linux-kernel - [PATCH v2 1/7] MIPS: cmdline: Add support for 'memmap' parameter

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Date:   Wed, 28 Jun 2017 17:56:25 +0200
From:   Aleksandar Markovic <aleksandar.markovic@...rk.com>
To:     linux-mips@...ux-mips.org
Cc:     Miodrag Dinic <miodrag.dinic@...tec.com>,
        Goran Ferenc <goran.ferenc@...tec.com>,
        Aleksandar Markovic <aleksandar.markovic@...tec.com>,
        Douglas Leung <douglas.leung@...tec.com>,
        James Hogan <james.hogan@...tec.com>,
        Jonas Gorski <jogo@...nwrt.org>, linux-kernel@...r.kernel.org,
        Marcin Nowakowski <marcin.nowakowski@...tec.com>,
        Paul Burton <paul.burton@...tec.com>,
        Petar Jovanovic <petar.jovanovic@...tec.com>,
        Raghu Gandham <raghu.gandham@...tec.com>,
        Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH v2 1/7] MIPS: cmdline: Add support for 'memmap' parameter

From: Miodrag Dinic <miodrag.dinic@...tec.com>

Implement support for parsing 'memmap' kernel command line parameter.

This patch covers parsing of the following two formats for 'memmap'
parameter values:

  - nn[KMG]@ss[KMG]
  - nn[KMG]$ss[KMG]

  ([KMG] = 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=nn[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=nn[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=64K$0x18690000
        or
        memmap=0x10000$0x18690000

There is no need to update this documentation file with respect to
this patch.

Signed-off-by: Miodrag Dinic <miodrag.dinic@...tec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@...tec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@...tec.com>
---
 arch/mips/kernel/setup.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index ccea90f..5a86da93 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -713,6 +713,46 @@ static int __init early_parse_mem(char *p)
 }
 early_param("mem", early_parse_mem);
 
+static int __init early_parse_memmap(char *p)
+{
+	char *oldp;
+	u64 start_at, mem_size;
+
+	if (!p)
+		return -EINVAL;
+
+	if (!strncmp(p, "exactmap", 8)) {
+		pr_err("\"memmap=exactmap\" invalid on MIPS\n");
+		return 0;
+	}
+
+	oldp = p;
+	mem_size = memparse(p, &p);
+	if (p == oldp)
+		return -EINVAL;
+
+	if (*p == '@') {
+		start_at = memparse(p+1, &p);
+		add_memory_region(start_at, mem_size, BOOT_MEM_RAM);
+	} else if (*p == '#') {
+		pr_err("\"memmap=nn#ss\" (force ACPI data) invalid on MIPS\n");
+		return -EINVAL;
+	} else if (*p == '$') {
+		start_at = memparse(p+1, &p);
+		add_memory_region(start_at, mem_size, BOOT_MEM_RESERVED);
+	} else {
+		pr_err("\"memmap\" invalid format!\n");
+		return -EINVAL;
+	}
+
+	if (*p == '\0') {
+		usermem = 1;
+		return 0;
+	} else
+		return -EINVAL;
+}
+early_param("memmap", early_parse_memmap);
+
 #ifdef CONFIG_PROC_VMCORE
 unsigned long setup_elfcorehdr, setup_elfcorehdr_size;
 static int __init early_parse_elfcorehdr(char *p)
-- 
2.7.4