On Tue, Oct 24, 2017 at 09:18:47AM +0200, Hannes Reinecke wrote:

Can we have some information in sysfs to figure out if a gendisk is
hidden? I'd hate having to do an inverse lookup in /proc/partitions;
it's always hard to prove that something is _not_ present.
And we already present various information (like disk_removable_show()),
so it's not without precedent.
And it would make integration with systemd/udev easier.

Sure, I'll add a hidden flag sysfs file.