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Feel free to set the default to 'disabled' when > CONFIG_PREEMPT_RT is set. Will do. I'll add a bool mount option (e.g. statfs_capacity) that, when disabled, skips QueryVariableInfo() in statfs() and reports 0 used/available, defaulting to disabled under CONFIG_PREEMPT_RT. If you'd rather df still show numbers without the per-statfs firmware call, I could instead prime the value once at mount and serve that (stale but non-zero) as a "cached" mode -- i.e. a tri-state option: statfs_capacity=live|cached|off live - current behaviour: rate-limited QueryVariableInfo() on statfs() cached - prime once at mount, serve the static value (no per-statfs call) off - report 0 used/available (no firmware call at all) default: live on non-RT, off on CONFIG_PREEMPT_RT Happy either way. Thanks, Prashant