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List:       linux-s390
Subject:    Re: [PATCH v2 3/3] device-dax: Add system ram (add_memory()) with MHP_NO_FIRMWARE_MEMMAP
From:       David Hildenbrand <david () redhat ! com>
Date:       2020-04-30 15:28:29
Message-ID: 0e30697f-a5f7-e272-6aa5-8c7197c15818 () redhat ! com
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On 30.04.20 13:23, Dave Hansen wrote:
> On 4/30/20 3:29 AM, David Hildenbrand wrote:
>> Currently, when adding memory, we create entries in /sys/firmware/memmap/
>> as "System RAM". This does not reflect the reality and will lead to
>> kexec-tools to add that memory to the fixed-up initial memmap for a
>> kexec kernel (loaded via kexec_load()). The memory will be considered
>> initial System RAM by the kexec kernel.
>>
>> We should let the kexec kernel decide how to use that memory - just as
>> we do during an ordinary reboot.
> ...
>> -	rc = add_memory(numa_node, new_res->start, resource_size(new_res), 0);
>> +	rc = add_memory(numa_node, new_res->start, resource_size(new_res),
>> +			MHP_NO_FIRMWARE_MEMMAP);
> 
> Looks fine.  But, if you send another revision, could you add a comment
> about the actual goal of MHP_NO_FIRMWARE_MEMMAP?  Maybe:
> 
> 	/*
> 	 * MHP_NO_FIRMWARE_MEMMAP ensures that future
> 	 * kexec'd kernels will not treat this as RAM.
> 	 */
> 
> Not a biggie, though.

Sure, maybe Andrew can fixup when applying (if no resend is necessary).

Thanks Dave!

> 
> Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
> 


-- 
Thanks,

David / dhildenb

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