Going thru xenomai Kconfig again, some observations/uncertainties came up.
I'll make a patch, given feedback.


"Aperiodic mode provides for non-constant delays between timer ticks,"

the wording here (non-constant delays) left me momentarily wondering
if _APERIODIC was bad (this, despite the use of 'provides'). Maybe "sub-tick delays" makes some sense ..


Are there any decent estimates or examples of the latency / jitter increases
if this is enabled ?  Is it highly cpu or chipset dependent ?
I presume /proc/interrupts is the place to look to see if you might need it,
iff any of the devices of interest are shared.
my laptop shows sharing, my soekris does not

 3:          5          XT-PIC  ehci_hcd:usb1, ohci1394
 4:          0          XT-PIC  uhci_hcd:usb6
 7:     708975          XT-PIC  ipw2200, ehci_hcd:usb2, uhci_hcd:usb7
 8:          1          XT-PIC  rtc
9: 437509 XT-PIC acpi, Intel 82801DB-ICH4, Intel 82801DB-ICH4 Modem, ohci_hcd:usb3, ohci_hcd:usb4, uhci_hcd:usb5, yenta, eth0

# cat /proc/interrupts
 0:   13148086          XT-PIC  timer
 2:          0          XT-PIC  cascade
 4:      33084          XT-PIC  serial
 8:          4          XT-PIC  rtc
10:     337134          XT-PIC  eth0
11:     926639          XT-PIC  ndiswrapper
14:         11          XT-PIC  ide0
NMI:          0


does this only apply to ISA bus ?


will add module name


Note that the preferred
way of implementing generic drivers usable across all Xenomai
interfaces is defined by the Real-Time Driver Model (RTDM).

It doesnt say theyre (in)?compatible, should it ?


Id like to see estimates of the latency costs associated with each choice,
where its practical to do so (given the current unknowables, like variations across
cpus, chipsets etc).  I recognize that such numbers are the hoped-for
end result of the xenomai-data ML, and perhaps nothing real can be said
yet (or ever) in Kconfig, except in (overly?) broad statements.

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