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

[Charlie Jenkins <charlie@rivosinc.com>]

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