To return to the original subject ...
/n/sources/contrib/miller/9pi2 is a Plan 9 kernel which runs on the
Raspberry Pi 2 (one core only, so far). I'll put updated source
in contrib/miller/9/bcm later today. mk CONF'='pi2 for the new
model, CONF'='pi for the original model.
Plan 9 from Bell Labs
firmware: rev 1422642103
cpu0: 900MHz ARM Cortex-A7 r0p5
fp: 32 registers, simd
fp: arm arch VFPv3+ with common VFP subarch v2; rev 5
eMMC external clock 250 Mhz
#u/usb/ep1.0: dwcotg: port 0X0 irq 9
992M memory: 200M kernel data, 792M user, 3762M swap
usb/hub... usb/ether...
etherusb smsc: b827eb4f2fbd
usb/kb... usb/kb... root is from (local, tcp)[local]: tcp
Even with one core activated, the rpi2 is noticeably quicker than
the rpi. Decoding a 1600x1200 jpeg with 'jpg -t' (from ramfs)
takes about 5.8s on rpi, 3.2s on rpi2.
Note that the publicity says 900Mhz, but the firmware boots at
600Mhz, and relies on dynamic clock and voltage management in
linux to adjust the speed. To get a fixed 900Mhz speed, I put
this in config.txt:
kernel=9pi2
gpu_mem=16
disable_overscan=1
arm_freq=900
force_turbo=1
Disclaimer: if you put silly numbers in arm_freq, bad stuff
might happen. Supposedly the firmware detects this and sets
an irreversible bit somewhere that voids your warranty.