Dave Martin <Dave.Martin@xxxxxxx> writes: > On Mon, Oct 09, 2017 at 10:34:25AM +0100, Alex Bennée wrote: >> >> Dave Martin <Dave.Martin@xxxxxxx> writes: >> >> > On Fri, Oct 06, 2017 at 04:43:43PM +0100, Szabolcs Nagy wrote: >> >> On 31/08/17 18:00, Dave Martin wrote: >> >> > +9. System runtime configuration >> >> > +-------------------------------- >> >> > + >> >> > +* To mitigate the ABI impact of expansion of the signal frame, a policy >> >> > + mechanism is provided for administrators, distro maintainers and developers >> >> > + to set the default vector length for userspace processes: >> >> > + >> >> > +/proc/cpu/sve_default_vector_length >> >> >> >> >> >> elsewhere in the patch series i see >> >> >> >> /proc/sys/abi/sve_default_vector_length >> >> >> >> is this supposed to be the same? >> > >> > Good spot, thanks! >> > >> > /proc/cpu/ was the old location: they should both say /proc/abi/. >> > I'll fix it. >> >> Isn't /sys (or rather sysfs) the preferred location for modern control >> knobs that mirror the kernels object model or is SVE a special case for >> extending /proc? > > I couldn't figure out which kernel object this maps to. There's no > device, no driver. This isn't even per-cpu. Hmm I can see: /sys/devices/system/cpu On both my x86 and arm64 systems - but I guess this is more ABIish than CPU feature related. > sysctl is already used for similar knobs to this one, so I followed that > precedent -- though if someone argues strongly enough it could be > changed. > > Are there already examples of arch controls like this in sysfs? I > wasn't aware of any, but I didn't look all that hard... Given the paucity of the /proc/sys/abi on both systems I guess this sort of knob is rare enough that people haven't expressed a strong preference for sysfs here. I have no objection to staying with /proc/sys/abi/. -- Alex Bennée _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
