[rds-devel] [PATCH RFC v1] rds: Expose feature parameters via sysfs and ELF note

[Andrew Lunn]

> +What:		/sys/module/rds/parameters/rds_ioctl_set_tos
> +Date:		Jun 2025
> +Contact:	rds-devel at oss.oracle.com
> +Description:
> +		The RDS driver supports the mechanism to set on a socket
> +		the Quality of Service.
> +
> +		The returned value is the socket ioctl number and this is read-only.

>From this, can i imply that the IOCTL number has changed sometime in
the past? That would be an ABI break, which is not good.

More likely, none of the IOCTL numbers have changed. All you need to
know is if the file exists or not. So i would makes the files the same
as /dev/null.

Also, these are not actually parameters to the module, so putting them
in parameters seems confusing at best.

I doubt this is the first time this problem has been addressed in the
kernel. Maybe look at:

$ find /sys -name "*features*"
/sys/kernel/security/apparmor/features
/sys/kernel/cgroup/features

and see if you can copy/paste ideas/code from there. And also ask them
if this was a good idea, or they say not don't do that, it was a bad
idea, just call the IOCTL and test for ENOIOCTLCMD.

	Andrew