as a direct index into cpus.  Record apicid in struct cpu and have cpunum() look
for it. Replace cpu->id with cpunum() everywhere, and replace cpu->id with cpu->apicid.
Thanks to Xi Wang.

add to test that they indeed trap in user space
thanks to pablogventura@gmail.com and nwolovick@gmail.com

 for f in *.{h,c}; do sed -i .sed 's/[[:blank:]]*$//' $f; done
(Thanks to Nicolás Wolovick)

that is a multiple of the sector size.

however, processes still modify their own p->* without locking

* use xchg only for its atomicness.
* use __sync_synchronize() for both CPU and compiler barrier.

fix Regehr complaint

Use cons.lock for everything.  This eliminates the possibility that two CPUS
independently, simultaneously manipulate the CRTC in cgaputc.

Fix comments

Update URL for 2014