Now parse_crashkernel() is a real entry point for all kinds of
crahskernel parsing on any architecture.

And wrap the crahskernel=,high|low handling inside
CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  6 ++++++
 kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 2e76289699ff..85260bf4a734 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
 void final_note(Elf_Word *buf);
 
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
+#endif
+#endif
+
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base,
 		unsigned long long *low_size, bool *high);
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index f6a5c219e2e1..355b0ab5189c 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
 /*
  * That function is the entry point for command line parsing and should be
  * called from the arch-specific code.
+ *
+ * If crashkernel=,high|low is supported on architecture, non-NULL values
+ * should be passed to parameters 'low_size' and 'high'.
  */
 int __init parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
@@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
 				crash_base, NULL);
 	if (!high)
 		return ret;
-
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	else if (ret == -ENOENT) {
+		ret = __parse_crashkernel(cmdline, 0, crash_size,
+				crash_base, suffix_tbl[SUFFIX_HIGH]);
+		if (ret || !*crash_size)
+			return -1;
+
+		/*
+		 * crashkernel=Y,low can be specified or not, but invalid value
+		 * is not allowed.
+		 */
+		ret = __parse_crashkernel(cmdline, 0, low_size,
+				crash_base, suffix_tbl[SUFFIX_LOW]);
+		if (ret == -ENOENT)
+			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
+		else if (ret)
+			return -1;
+
+		*high = true;
+	} else if (ret || !*crash_size) {
+		/* The specified value is invalid */
+		return -1;
+	}
+#endif
 	return 0;
 }
 
-- 
2.41.0

On 2023/8/29 20:16, Baoquan He wrote:
> Now parse_crashkernel() is a real entry point for all kinds of
> crahskernel parsing on any architecture.
> 
> And wrap the crahskernel=,high|low handling inside
> CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/crash_core.h |  6 ++++++
>  kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 2e76289699ff..85260bf4a734 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
>  void final_note(Elf_Word *buf);
>  
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> +#endif
> +#endif
> +
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base,
>  		unsigned long long *low_size, bool *high);
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index f6a5c219e2e1..355b0ab5189c 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
>  /*
>   * That function is the entry point for command line parsing and should be
>   * called from the arch-specific code.
> + *
> + * If crashkernel=,high|low is supported on architecture, non-NULL values
> + * should be passed to parameters 'low_size' and 'high'.
>   */
>  int __init parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
> @@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
>  				crash_base, NULL);
>  	if (!high)
>  		return ret;
> -
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +	else if (ret == -ENOENT) {
> +		ret = __parse_crashkernel(cmdline, 0, crash_size,
> +				crash_base, suffix_tbl[SUFFIX_HIGH]);
> +		if (ret || !*crash_size)
> +			return -1;

Change -1 to -EINVAL?

> +
> +		/*
> +		 * crashkernel=Y,low can be specified or not, but invalid value
> +		 * is not allowed.
> +		 */
> +		ret = __parse_crashkernel(cmdline, 0, low_size,
> +				crash_base, suffix_tbl[SUFFIX_LOW]);
> +		if (ret == -ENOENT)
> +			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> +		else if (ret)
> +			return -1;

return ret;

> +
> +		*high = true;
> +	} else if (ret || !*crash_size) {

This check can be moved outside of #ifdef. Because even '!high', it's completely
applicable. The overall adjustment is as follows:

-  	if (!high)
-  		return ret;

#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		... ...
		if (ret || !*crash_size)	//parse HIGH
		... ...
	}

	//At this point, *crash_size is not 0 and ret is 0.
	//We can also delete if (!*crash_size) above because it will be checked later.
#endif

	if (!*crash_size)
		ret = -EINVAL;

	return ret;

-  	return 0;

> +		/* The specified value is invalid */
> +		return -1;
> +	}
> +#endif
>  	return 0;
>  }
>  
> 

-- 
Regards,
  Zhen Lei

On 08/31/23 at 10:56am, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/8/29 20:16, Baoquan He wrote:
> > Now parse_crashkernel() is a real entry point for all kinds of
> > crahskernel parsing on any architecture.
> > 
> > And wrap the crahskernel=,high|low handling inside
> > CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  include/linux/crash_core.h |  6 ++++++
> >  kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
> >  2 files changed, 33 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> > index 2e76289699ff..85260bf4a734 100644
> > --- a/include/linux/crash_core.h
> > +++ b/include/linux/crash_core.h
> > @@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> >  			  void *data, size_t data_len);
> >  void final_note(Elf_Word *buf);
> >  
> > +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> > +#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> > +#endif
> > +#endif
> > +
> >  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
> >  		unsigned long long *crash_size, unsigned long long *crash_base,
> >  		unsigned long long *low_size, bool *high);
> > diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> > index f6a5c219e2e1..355b0ab5189c 100644
> > --- a/kernel/crash_core.c
> > +++ b/kernel/crash_core.c
> > @@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
> >  /*
> >   * That function is the entry point for command line parsing and should be
> >   * called from the arch-specific code.
> > + *
> > + * If crashkernel=,high|low is supported on architecture, non-NULL values
> > + * should be passed to parameters 'low_size' and 'high'.
> >   */
> >  int __init parse_crashkernel(char *cmdline,
> >  			     unsigned long long system_ram,
> > @@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
> >  				crash_base, NULL);
> >  	if (!high)
> >  		return ret;
> > -
> > +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > +	else if (ret == -ENOENT) {
> > +		ret = __parse_crashkernel(cmdline, 0, crash_size,
> > +				crash_base, suffix_tbl[SUFFIX_HIGH]);
> > +		if (ret || !*crash_size)
> > +			return -1;
> 
> Change -1 to -EINVAL?

Thanks a lot for careful reviewing, Zhen Lei.

Here, it's fine to me, parse_crashkernel() returns 0 on success, other value
on failure. '-1' or '-EINVAL' is not different to me in this case. I can
update if you think '-EINVAL' is better.

> 
> > +
> > +		/*
> > +		 * crashkernel=Y,low can be specified or not, but invalid value
> > +		 * is not allowed.
> > +		 */
> > +		ret = __parse_crashkernel(cmdline, 0, low_size,
> > +				crash_base, suffix_tbl[SUFFIX_LOW]);
> > +		if (ret == -ENOENT)
> > +			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> > +		else if (ret)
> > +			return -1;
> 
> return ret;

Ditto.

> 
> > +
> > +		*high = true;
> > +	} else if (ret || !*crash_size) {
> 
> This check can be moved outside of #ifdef. Because even '!high', it's completely
> applicable. The overall adjustment is as follows:

Hmm, the current logic is much easier to understand. However, I may not
100% get your suggestion. Can you paste the complete code in your
suggested way? Do not need 100% correct code, just the skeleton of code logic
so that I can better understand it and add inline comment.

> 
> -  	if (!high)
> -  		return ret;
> 
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		... ...
> 		if (ret || !*crash_size)	//parse HIGH
> 		... ...
> 	}
> 
> 	//At this point, *crash_size is not 0 and ret is 0.
> 	//We can also delete if (!*crash_size) above because it will be checked later.
> #endif
> 
> 	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;

When crashkernel=,high is specified while crashkernel=,low is omitted,
the ret==-ENOENT, but we can't return ret directly. That is still an
acceptable way.

> 
> -  	return 0;
> 
> > +		/* The specified value is invalid */
> > +		return -1;
> > +	}
> > +#endif
> >  	return 0;
> >  }
> >  
> > 
> 
> -- 
> Regards,
>   Zhen Lei
>

On 2023/9/1 17:49, Baoquan He wrote:
>>> +
>>> +		*high = true;
>>> +	} else if (ret || !*crash_size) {
>> This check can be moved outside of #ifdef. Because even '!high', it's completely
>> applicable. The overall adjustment is as follows:
> Hmm, the current logic is much easier to understand. However, I may not
> 100% get your suggestion. Can you paste the complete code in your
> suggested way? Do not need 100% correct code, just the skeleton of code logic
> so that I can better understand it and add inline comment.

int __init parse_crashkernel(...)
{
	int ret;

	/* crashkernel=X[@offset] */
	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
				crash_base, NULL);

#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
		ret = 0;	//Added based on the next discussion
	}
+#endif

 	if (!*crash_size)
		ret = -EINVAL;

	return ret;
}

> 
>> -  	if (!high)
>> -  		return ret;
>>
>> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>> 	if (high && ret == -ENOENT) {
>> 		... ...
>> 		if (ret || !*crash_size)	//parse HIGH
>> 		... ...
>> 	}
>>
>> 	//At this point, *crash_size is not 0 and ret is 0.
>> 	//We can also delete if (!*crash_size) above because it will be checked later.
>> #endif
>>
>> 	if (!*crash_size)
>> 		ret = -EINVAL;
>>
>> 	return ret;
> When crashkernel=,high is specified while crashkernel=,low is omitted,
> the ret==-ENOENT, but we can't return ret directly. That is still an
> acceptable way.

Oh, yes. Sorry, I didn't notice branch "ret==-ENOENT" didn't return. So "ret = 0;"
needs to be added.

	if (high && ret == -ENOENT) {
		... ...
		*high = true;
+		ret = 0;
	}

> 
>> -  	return 0;
>>
>>> +		/* The specified value is invalid */
>>> +		return -1;
>>> +	}
>>> +#endif
>>>  	return 0;
>>>  }
>>>  
>>>

-- 
Regards,
  Zhen Lei

On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/9/1 17:49, Baoquan He wrote:
> >>> +
> >>> +		*high = true;
> >>> +	} else if (ret || !*crash_size) {
> >> This check can be moved outside of #ifdef. Because even '!high', it's completely
> >> applicable. The overall adjustment is as follows:
> > Hmm, the current logic is much easier to understand. However, I may not
> > 100% get your suggestion. Can you paste the complete code in your
> > suggested way? Do not need 100% correct code, just the skeleton of code logic
> > so that I can better understand it and add inline comment.
> 
> int __init parse_crashkernel(...)
> {
> 	int ret;
> 
> 	/* crashkernel=X[@offset] */
> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> 				crash_base, NULL);
> 
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
> 		ret = 0;	//Added based on the next discussion
> 	}
> +#endif
> 
>  	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;
> }
> 
Thanks, Zhen Lei.

I paste the whole parse_crashkernel() as you suggested at bottom. Please
check if it's what you want. To me, both is fine to me. I have two minor
concerns to your suggested way.

1)
I took the "if (!high) return" way because except of x86/arm64, all
other architectures will call parse_crashkerne() and check
if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
and check those call sites. With that, we will have duplicated checking.

        ret = __parse_crashkernel(cmdline, system_ram, crash_size,
                                crash_base, NULL);
        if (!high)
                return ret;
2)
I actually like below branch and the code comment. It can give people
hint about what's going on in that case. Discarding it is a little pity.

        } else if (ret || !*crash_size) {
                /* The specified value is invalid */
                return -1;
        }

int __init parse_crashkernel(...)
{
	int ret;

	/* crashkernel=X[@offset] */
	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
				crash_base, NULL);
#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		ret = __parse_crashkernel(cmdline, 0, crash_size,
				crash_base, suffix_tbl[SUFFIX_HIGH]);
		if (ret || !*crash_size)
			return -EINVAL;

		/*
		 * crashkernel=Y,low can be specified or not, but invalid value
		 * is not allowed.
		 */
		ret = __parse_crashkernel(cmdline, 0, low_size,
				crash_base, suffix_tbl[SUFFIX_LOW]);
		if (ret == -ENOENT) {
			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
			ret = 0;
		} else if (ret) {
			return ret;
		}

		*high = true;
	}
#endif

	if (!*crash_size)
		ret = -EINVAL;

	return ret;
}

On 2023/9/5 16:29, Baoquan He wrote:
> On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2023/9/1 17:49, Baoquan He wrote:
>>>>> +
>>>>> +		*high = true;
>>>>> +	} else if (ret || !*crash_size) {
>>>> This check can be moved outside of #ifdef. Because even '!high', it's completely
>>>> applicable. The overall adjustment is as follows:
>>> Hmm, the current logic is much easier to understand. However, I may not
>>> 100% get your suggestion. Can you paste the complete code in your
>>> suggested way? Do not need 100% correct code, just the skeleton of code logic
>>> so that I can better understand it and add inline comment.
>>
>> int __init parse_crashkernel(...)
>> {
>> 	int ret;
>>
>> 	/* crashkernel=X[@offset] */
>> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
>> 				crash_base, NULL);
>>
>> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>> 	if (high && ret == -ENOENT) {
>> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
>> 		ret = 0;	//Added based on the next discussion
>> 	}
>> +#endif
>>
>>  	if (!*crash_size)
>> 		ret = -EINVAL;
>>
>> 	return ret;
>> }
>>
> Thanks, Zhen Lei.
> 
> I paste the whole parse_crashkernel() as you suggested at bottom. Please
> check if it's what you want. 

Yes.

> To me, both is fine to me. I have two minor
> concerns to your suggested way.
> 
> 1)
> I took the "if (!high) return" way because except of x86/arm64, all
> other architectures will call parse_crashkerne() and check
> if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
> and check those call sites. With that, we will have duplicated checking.

Add some patches to remove the duplicated checking of other ARCHs? After this
patch series upstreamed.

> 
>         ret = __parse_crashkernel(cmdline, system_ram, crash_size,
>                                 crash_base, NULL);
>         if (!high)
>                 return ret;
> 2)
> I actually like below branch and the code comment. It can give people
> hint about what's going on in that case. Discarding it is a little pity.

Except that "!*crash_size" and "(high && ret == -ENOENT)" needs special comments,
other common errors do not need to be described, I think. Even if some is required,
it should be placed in function __parse_crashkernel().

> 
>         } else if (ret || !*crash_size) {
>                 /* The specified value is invalid */
>                 return -1;
>         }
> 
> int __init parse_crashkernel(...)
> {
> 	int ret;
> 
> 	/* crashkernel=X[@offset] */
> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> 				crash_base, NULL);
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		ret = __parse_crashkernel(cmdline, 0, crash_size,
> 				crash_base, suffix_tbl[SUFFIX_HIGH]);
> 		if (ret || !*crash_size)
> 			return -EINVAL;
> 
> 		/*
> 		 * crashkernel=Y,low can be specified or not, but invalid value
> 		 * is not allowed.
> 		 */
> 		ret = __parse_crashkernel(cmdline, 0, low_size,
> 				crash_base, suffix_tbl[SUFFIX_LOW]);
> 		if (ret == -ENOENT) {
> 			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> 			ret = 0;
> 		} else if (ret) {
> 			return ret;
> 		}
> 
> 		*high = true;
> 	}
> #endif
> 
> 	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;
> }
> 
> .
> 

-- 
Regards,
  Zhen Lei

On 09/06/23 at 05:07pm, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/9/5 16:29, Baoquan He wrote:
> > On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
> >>
> >>
> >> On 2023/9/1 17:49, Baoquan He wrote:
> >>>>> +
> >>>>> +		*high = true;
> >>>>> +	} else if (ret || !*crash_size) {
> >>>> This check can be moved outside of #ifdef. Because even '!high', it's completely
> >>>> applicable. The overall adjustment is as follows:
> >>> Hmm, the current logic is much easier to understand. However, I may not
> >>> 100% get your suggestion. Can you paste the complete code in your
> >>> suggested way? Do not need 100% correct code, just the skeleton of code logic
> >>> so that I can better understand it and add inline comment.
> >>
> >> int __init parse_crashkernel(...)
> >> {
> >> 	int ret;
> >>
> >> 	/* crashkernel=X[@offset] */
> >> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> >> 				crash_base, NULL);
> >>
> >> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> >> 	if (high && ret == -ENOENT) {
> >> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
> >> 		ret = 0;	//Added based on the next discussion
> >> 	}
> >> +#endif
> >>
> >>  	if (!*crash_size)
> >> 		ret = -EINVAL;
> >>
> >> 	return ret;
> >> }
> >>
> > Thanks, Zhen Lei.
> > 
> > I paste the whole parse_crashkernel() as you suggested at bottom. Please
> > check if it's what you want. 
> 
> Yes.
> 
> > To me, both is fine to me. I have two minor
> > concerns to your suggested way.
> > 
> > 1)
> > I took the "if (!high) return" way because except of x86/arm64, all
> > other architectures will call parse_crashkerne() and check
> > if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
> > and check those call sites. With that, we will have duplicated checking.
> 
> Add some patches to remove the duplicated checking of other ARCHs? After this
> patch series upstreamed.

I resisted this in the first place, after rethinking, it makes sense.
parse_crashkernel() returning 0 indicates a meaningful crashkernel vlaue
parsed, otherwise non-zero. I will go with this.

> 
> > 
> >         ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> >                                 crash_base, NULL);
> >         if (!high)
> >                 return ret;
> > 2)
> > I actually like below branch and the code comment. It can give people
> > hint about what's going on in that case. Discarding it is a little pity.
> 
> Except that "!*crash_size" and "(high && ret == -ENOENT)" needs special comments,
> other common errors do not need to be described, I think. Even if some is required,
> it should be placed in function __parse_crashkernel().

Hmm, I will consider how to comment these better, will update and post
v3.

Thanks, Lei.

> 
> > 
> >         } else if (ret || !*crash_size) {
> >                 /* The specified value is invalid */
> >                 return -1;
> >         }
> > 
> > int __init parse_crashkernel(...)
> > {
> > 	int ret;
> > 
> > 	/* crashkernel=X[@offset] */
> > 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> > 				crash_base, NULL);
> > #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > 	if (high && ret == -ENOENT) {
> > 		ret = __parse_crashkernel(cmdline, 0, crash_size,
> > 				crash_base, suffix_tbl[SUFFIX_HIGH]);
> > 		if (ret || !*crash_size)
> > 			return -EINVAL;
> > 
> > 		/*
> > 		 * crashkernel=Y,low can be specified or not, but invalid value
> > 		 * is not allowed.
> > 		 */
> > 		ret = __parse_crashkernel(cmdline, 0, low_size,
> > 				crash_base, suffix_tbl[SUFFIX_LOW]);
> > 		if (ret == -ENOENT) {
> > 			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> > 			ret = 0;
> > 		} else if (ret) {
> > 			return ret;
> > 		}
> > 
> > 		*high = true;
> > 	}
> > #endif
> > 
> > 	if (!*crash_size)
> > 		ret = -EINVAL;
> > 
> > 	return ret;
> > }
> > 
> > .
> > 
> 
> -- 
> Regards,
>   Zhen Lei
>