Re: [PATCH 3/4] ACPI/MRRM: Add "node" symlink to /sys/devices/system/memory/rangeX

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Feb 11, 2025 at 05:02:11PM +0000, Luck, Tony wrote:
> >> +	if (node)
> >> +		ret = sysfs_create_link(&entry->dev.kobj, &node->dev.kobj, "node");
> >
> > What is going to remove this symlink if the memory goes away?  Or do
> > these never get removed?
> 
> There's currently no method for runtime changes to these memory ranges. They
> are described by a static ACPI table.  I need to poke the folks that came up
> with this to ask how memory hotplug will be handled (since CXL seems to be
> making that fashionable again).

ACPI should be supporting memory hotplug today, at the very least
"memory add", so surely you have some old boxes to test this with?

> > symlinks in sysfs created like this always worry me.  What is going to
> > use it?
> 
> <hand waves>User space tools that want to understand what the "per-region"
> monitoring and control features are actually operating on.</hand waves>

If you don't have a real user today, please don't include it now.  Wait
until it is actually needed.

thanks,

greg k-h