Le 15/06/2017 à 10:28, Manuel Bouyer a écrit :
On Thu, Jun 15, 2017 at 10:11:21AM +0200, Maxime Villard wrote:
There were several strong objections to our change in this thread: http://mail-index.netbsd.org/tech-kern/2017/03/28/msg021705.html
Man, that's another thread. My commit is about PMCs, not rdtsc.
OK I got confused. then where was this change discussed ?
nowhere
IHMO the same arguments from the thread applies here.
Which argument? fyi, pmcs are not enabled by default, and until a few months ago they didn't even work. I'm making them privileged with the intention of enabling them for real. The reasons we need root privileges are: the msr values are given by userland and we don't want unprivileged users to panic the system, and more generally, pmcs can be used to defeat aslr (as said in the thread, btw).