[PATCH] powerpc/fadump: sysfs for fadump memory reservation

[Sourabh Jain]

On 8/7/19 8:40 AM, Michael Ellerman wrote:
> Sourabh Jain <sourabhjain at linux.ibm.com> writes:
>> Add a sys interface to allow querying the memory reserved by fadump
>> for saving the crash dump.
>>
>> Signed-off-by: Sourabh Jain <sourabhjain at linux.ibm.com>
>> ---
>>  Documentation/powerpc/firmware-assisted-dump.rst |  5 +++++
>>  arch/powerpc/kernel/fadump.c                     | 14 ++++++++++++++
>>  2 files changed, 19 insertions(+)
>>
>> diff --git a/Documentation/powerpc/firmware-assisted-dump.rst b/Documentation/powerpc/firmware-assisted-dump.rst
>> index 9ca12830a48e..4a7f6dc556f5 100644
>> --- a/Documentation/powerpc/firmware-assisted-dump.rst
>> +++ b/Documentation/powerpc/firmware-assisted-dump.rst
>> @@ -222,6 +222,11 @@ Here is the list of files under kernel sysfs:
>>      be handled and vmcore will not be captured. This interface can be
>>      easily integrated with kdump service start/stop.
>>  
>> +/sys/kernel/fadump_mem_reserved
>> +
>> +   This is used to display the memory reserved by fadump for saving the
>> +   crash dump.
>> +
>>   /sys/kernel/fadump_release_mem
>>      This file is available only when fadump is active during
>>      second kernel. This is used to release the reserved memory
> 
> Dumping these in /sys/kernel is pretty gross, but I guess that ship has
> sailed.
> 
> But please add it to Documentation/ABI, and Cc the appropriate lists/people.

Sure, I will write the ABI documentation and will send the next version.

> 
> cheers
> 
>> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
>> index 4eab97292cc2..70d49013ebec 100644
>> --- a/arch/powerpc/kernel/fadump.c
>> +++ b/arch/powerpc/kernel/fadump.c
>> @@ -1514,6 +1514,13 @@ static ssize_t fadump_enabled_show(struct kobject *kobj,
>>  	return sprintf(buf, "%d\n", fw_dump.fadump_enabled);
>>  }
>>  
>> +static ssize_t fadump_mem_reserved_show(struct kobject *kobj,
>> +					struct kobj_attribute *attr,
>> +					char *buf)
>> +{
>> +	return sprintf(buf, "%ld\n", fw_dump.reserve_dump_area_size);
>> +}
>> +
>>  static ssize_t fadump_register_show(struct kobject *kobj,
>>  					struct kobj_attribute *attr,
>>  					char *buf)
>> @@ -1632,6 +1639,9 @@ static struct kobj_attribute fadump_attr = __ATTR(fadump_enabled,
>>  static struct kobj_attribute fadump_register_attr = __ATTR(fadump_registered,
>>  						0644, fadump_register_show,
>>  						fadump_register_store);
>> +static struct kobj_attribute fadump_mem_reserved_attr =
>> +			__ATTR(fadump_mem_reserved, 0444,
>> +			fadump_mem_reserved_show, NULL);
>>  
>>  DEFINE_SHOW_ATTRIBUTE(fadump_region);
>>  
>> @@ -1663,6 +1673,10 @@ static void fadump_init_files(void)
>>  			printk(KERN_ERR "fadump: unable to create sysfs file"
>>  				" fadump_release_mem (%d)\n", rc);
>>  	}
>> +	rc = sysfs_create_file(kernel_kobj, &fadump_mem_reserved_attr.attr);
>> +	if (rc)
>> +		pr_err("unable to create sysfs file fadump_mem_reserved (%d)\n",
>> +			rc);
>>  	return;
>>  }
>>  
>> -- 
>> 2.17.2