I am trying to boot the kernel with isolcpus=0 in an attempt to improve latency with the Xenomai kernel. As far as I can tell the way to do this with u-Boot is to edit the environement, ie "setenv bootargs isolcpus=0" setenv is "Command Unknown" in the standard shell, so I have concluded that this needs to be done in the serial boot shell. (Right or wrong?) But this doesn't seem to work: printenv > bootargs=isolcpus=0 xeno_hal.supported_cpus=1 cat /proc/cmdline > console=ttymxc1,115200 root=/dev/mmcblk0p1 rootwait rw fbmem=24M video=mxcfb0:dev=hdmi,1920x1080M@60,bpp=32 (dmesg looks the same). So, if editing bootargs _isn't_ the way to add a kernel boot parameter, what is the way? On IRC I was told to "recompile the kernel with the right options" but I thought I would seek a second opinion before taking the step of figuring out what the "right options" are.