SMP IRQ Affinity in L4android

Stefan Kalkowski stefan.kalkowski at ...1...
Mon Nov 16 08:47:38 CET 2015

Hi Li,

Just a few notes: we did not port L4Linux ability to directly use
hardware resources like interrupts and I/O memory. Instead we use
L4Linux in its para-virtualized form only. So within L4Android you can
use virtual interrupts delivered by other software components only.
The affinity setting seems to work as expected from what you have
described. Linux' proc filesystem's view is probably not synchronized
with the interrupt settings of the L4 kernel correctly. Maybe it always
shows CPU zero regardless of the actual IRQ state. Have you ever tried
to run L4Linux/L4Android in its original version on top of
Fiasco.OC/L4Re? Does that version delivers correct values via the proc
filesystem? Lastly, I have to admit that we do not use or test this old
port of L4Android (2.3) anymore.


On 11/09/2015 01:32 PM, li94575 wrote:
> Hi, everyone
> I want to move some interrupts to specified cpu core, but I encountered some difficulties. 
> When I try to write to "/proc/irq/*/smp_affinity" with cpu bitmask, it will call the interface l4lx_irq_dev_set_affinity(), which locates in "pots-foc/src/lib/l4lx/". And I can see the printed log "switched irq * to cpu* ". However, in fact, it doesnot work, the irq is still staying on previous cpu core ( seeing "/proc/interrupts") .
> Please tell me how can I do, thank you so much!
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Stefan Kalkowski
Genode Labs ยท

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