[PATCH v2] RISC-V: cmdline: Add support for 'memmap' parameter

[Punit Agrawal]

Hi Palmer,

Charlie Jenkins <charlie at rivosinc.com> 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]$ss[KMG]: mark specified memory as reserved;
>> 
>> Signed-off-by: Yunhui Cui <cuiyunhui at bytedance.com>
>> ---
>>  arch/riscv/mm/init.c | 46 ++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 46 insertions(+)
>> 
>> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
>> index e3405e4b99af..8e1d93ae5cb2 100644
>> --- a/arch/riscv/mm/init.c
>> +++ b/arch/riscv/mm/init.c
>> @@ -208,6 +208,52 @@ static int __init early_mem(char *p)
>>  }
>>  early_param("mem", early_mem);
>>  
>> +static void __init parse_memmap_one(char *p)
>> +{
>> +	char *oldp;
>> +	unsigned long start_at, mem_size;
>> +
>> +	if (!p)
>> +		return;
>> +
>> +	oldp = p;
>> +	mem_size = memparse(p, &p);
>> +	if (p == oldp)
>> +		return;
>> +
>> +	switch (*p) {
>> +	case '@':
>> +		start_at = memparse(p + 1, &p);
>> +		memblock_add(start_at, mem_size);
>> +		break;
>> +
>> +	case '$':
>> +		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 at rivosinc.com>

Another patch that looks good to get merged if there are no further
comments.

Any chance this can be picked up for this cycle?