Raspberry Pi has line "FIQ: usb_fiq" in /proc/interrupts.
"VALUE=$((VALUE + VAL))" results "Illegal number" in dash (Raspberry Pi)
"VALUE=$((VALUE + $VAL))" works in dash, bash and busybox (OpenWrt).
The config() function of irqstats seems to contain a superfluous
semicolon, causing munin to choke on this plugin. This simple patch
fixes exactly that.
Source: patch "240-fix-irqstats" from OpenWrt
Author: Jorik Jonker