Re: [RFC PATCH 1/2] mem-hotplug: introduce sysfs `range' attribute

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

# Cced some people maybe interested in this topic.

On Mon, Mar 02, 2015 at 04:04:59AM +0000, Sheng Yong wrote:
> There may be memory holes in a memory section, and because of that we can
> not know the real size of the section. In order to know the physical memory
> area used int one memory section, we walks through iomem resources and
> report the memory range in /sys/devices/system/memory/memoryX/range, like,
> 
> root@ivybridge:~# cat /sys/devices/system/memory/memory0/range
> 00001000-0008efff
> 00090000-0009ffff
> 00100000-07ffffff
> 
> Signed-off-by: Sheng Yong <shengyong1@huawei.com>

About a year ago, there was a similar request/suggestion from a library
developer about exporting valid physical address range
(http://thread.gmane.org/gmane.linux.kernel.mm/115600).
Then, we tried some but didn't make it.

So if you try to solve this, please consider some points from that discussion:
- interface name: just 'range' might not be friendly, if the interface returns
  physicall address range, something like 'phys_addr_range' looks better.
- prefix '0x': if you display the value range in hex, prefixing '0x' might
  be better to avoid letting every parser to add it in itself.
- supporting node range: your patch is now just for memory block interface, but
  someone (like me) are interested in exporting easy "phys_addr <=> node number"
  mapping, so if your approach is easily extensible to node interface, it would
  be very nice to include node interface support too.

Thanks,
Naoya Horiguchi
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