On 2021/12/29 0:13, Borislav Petkov wrote:

On Tue, Dec 28, 2021 at 09:26:01PM +0800, Zhen Lei wrote:

quoted

Use parse_crashkernel_high_low() to bring the parsing of
"crashkernel=X,high" and the parsing of "crashkernel=Y,low" together, they
are strongly dependent, make code logic clear and more readable.

Suggested-by: Borislav Petkov <bp@alien8.de>

Yeah, doesn't look like something I suggested...

quoted

@@ -474,10 +472,9 @@ static void __init reserve_crashkernel(void)
 	/* crashkernel=XM */
 	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
 	if (ret != 0 || crash_size <= 0) {
-		/* crashkernel=X,high */
-		ret = parse_crashkernel_high(boot_command_line, total_mem,
-					     &crash_size, &crash_base);
-		if (ret != 0 || crash_size <= 0)
+		/* crashkernel=X,high and possible crashkernel=Y,low */
+		ret = parse_crashkernel_high_low(boot_command_line, &crash_size, &low_size);

So this calls parse_crashkernel() and when that one fails, it calls this
new weird parse high/low helper you added.

But then all three end up in the same __parse_crashkernel() worker
function which seems to do the actual parsing.

What I suggested and what would be real clean is if the arches would
simply call a *single* 

	parse_crashkernel()

function and when that one returns, *all* crashkernel= options would
have been parsed properly, low, high, middle crashkernel, whatever...
and the caller would know what crash kernel needs to be allocated.

Then each arch can do its memory allocations and checks based on that
parsed data and decide to allocate or bail.

However, only x86 currently supports "crashkernel=X,high" and "crashkernel=Y,low", and arm64
will also support it. It is not supported on other architectures. So changing parse_crashkernel()
is not appropriate unless a new function is introduced. But naming this new function isn't easy,
and the name parse_crashkernel_in_order() that I've named before doesn't seem to be good.
Of course, we can also consider changing parse_crashkernel() to another name, then use
parse_crashkernel() to parse all possible "crashkernel=" options in order, but this will cause
other architectures to change as well.

So it is getting there but it needs more surgery...

Thx.

-- 
Regards,
  Zhen Lei

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