"Although the information we release has been verified and shown to work to the best our knowledge, we cant be held accountable for bricked devices or roots gone wrong."
During the install process the onboard SSD is modified and a new partition is added, sda8.
sda8 stores our new /boot. Our old boot is on sda1.
On startup, sda1 mounts sda8 and calls "reboot/reboot.sh" to kickstart the kernel reloading.
/bin/busybox insmod /system/reboot/modules/x86_kexec.ko /bin/busybox insmod /system/reboot/modules/kexec.ko exec /system/reboot/kexec -f /system/reboot/bzImage --command-line="root=/dev/sda8 console=ttyS0,115200"
The first two lines insert our new modules to call kexec. The sony kernel was not built to support kexec, so we had to add it in. The last line calls kexec, and forces it to load our image, "bzImage" from reboot/ on sda8.
Our new kernel is mostly stock, based off the released Sony code [here] (todo: setup code repository), with one modification. It is modified to allow / to be mounted RW.