Re: [PATCH -next v3 1/2] riscv: kdump: Implement crashkernel=X,[high,low]

[chenjiahao (C)]

On 2023/4/7 20:03, Simon Horman wrote:
> On Fri, Apr 07, 2023 at 06:02:05AM +0800, Chen Jiahao wrote:
> > On riscv, the current crash kernel allocation logic is trying to
> > allocate within 32bit addressible memory region by default, if
> > failed, try to allocate without 4G restriction.
> >
> > In need of saving DMA zone memory while allocating a relatively large
> > crash kernel region, allocating the reserved memory top down in
> > high memory, without overlapping the DMA zone, is a mature solution.
> > Here introduce the parameter option crashkernel=X,[high,low].
> >
> > One can reserve the crash kernel from high memory above DMA zone range
> > by explicitly passing "crashkernel=X,high"; or reserve a memory range
> > below 4G with "crashkernel=X,low".
> >
> > Signed-off-by: Chen Jiahao <chenjiahao16@xxxxxxxxxx>
> ...
>
> > @@ -1180,14 +1206,37 @@ static void __init reserve_crashkernel(void)
> >   		return;
> >   	}
> >   
> > -	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> > +	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> >   				&crash_size, &crash_base);
> > -	if (ret || !crash_size)
> > +	if (ret == -ENOENT) {
> > +		/*
> > +		 * crashkernel=X,[high,low] can be specified or not, but
> > +		 * invalid value is not allowed.
> nit: Perhaps something like this would be easier to correlate with the
>       code that follows:
>
> 		/* Fallback to crashkernel=X,[high,low] */
Agreed, this would be more concise and accurate.
> > +		 */
> > +		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
> > +		if (ret || !crash_size)
> > +			return;
> > +
> > +		/*
> > +		 * crashkernel=Y,low is valid only when crashkernel=X,high
> > +		 * is passed and high memory is reserved successful.
> nit: s/successful/successfully/

I will fix above nits and resend another version later, thanks.


> > +		 */
> > +		ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
> > +		if (ret == -ENOENT)
> > +			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> > +		else if (ret)
> > +			return;
> > +
> > +		search_start = search_low_max;
> > +	} else if (ret || !crash_size) {
> > +		/* Invalid argument value specified */
> >   		return;
> > +	}
> ...