Re: [PATCH v4 2/2] pstore/ramoops: Add ramoops.mem_name= command line option

[Guenter Roeck <linux@roeck-us.net>]

On 6/11/24 14:56, Steven Rostedt wrote:
> From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
> 
> Add a method to find a region specified by reserve_mem=nn:align:name for
> ramoops. Adding a kernel command line parameter:
> 
>    reserve_mem=12M:4096:oops ramoops.mem_name=oops
> 
> Will use the size and location defined by the memmap parameter where it
> finds the memory and labels it "oops". The "oops" in the ramoops option
> is used to search for it.
> 
> This allows for arbitrary RAM to be used for ramoops if it is known that
> the memory is not cleared on kernel crashes or soft reboots.
> 
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> Changes since v3: https://lore.kernel.org/linux-trace-kernel/20240606150316.916395285@goodmis.org
> 
> - Change type of start and size to phys_addr_t
> 
>   fs/pstore/ram.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index b1a455f42e93..4311fcbc84f2 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -50,6 +50,10 @@ module_param_hw(mem_address, ullong, other, 0400);
>   MODULE_PARM_DESC(mem_address,
>   		"start of reserved RAM used to store oops/panic logs");
>   
> +static char *mem_name;
> +module_param_named(mem_name, mem_name, charp, 0400);
> +MODULE_PARM_DESC(mem_name, "name of kernel param that holds addr");
> +
>   static ulong mem_size;
>   module_param(mem_size, ulong, 0400);
>   MODULE_PARM_DESC(mem_size,
> @@ -914,6 +918,16 @@ static void __init ramoops_register_dummy(void)
>   {
>   	struct ramoops_platform_data pdata;
>   
> +	if (mem_name) {
> +		phys_addr_t start;
> +		phys_addr_t size;
> +
> +		if (reserve_mem_find_by_name(mem_name, &start, &size)) {
> +			mem_address = start;
> +			mem_size = size;
> +		}
> +	}
> +
>   	/*
>   	 * Prepare a dummy platform data structure to carry the module
>   	 * parameters. If mem_size isn't set, then there are no module