Re: [PATCH v2 3/3] device-dax: Add system ram (add_memory()) with MHP_NO_FIRMWARE_MEMMAP

Dave Hansen
2020-04-30T11:23:47Z

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.

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