On Fri 2018-01-12 11:44:48, Linus Torvalds wrote: > On Fri, Jan 12, 2018 at 11:38 AM, Pavel Machek wrote: > > > > I'll try to do the right thing. OTOH... I don't like the fact that > > kernel memory on my machine is currently readable, probably even from > > javascript. > > Oh, absolutely. I'm just saying that it's probably best to try to > start from the x86-64 KPTI model, and see how that works for x86-32. > > Maybe some of the 4G:4G entry code could come in handy as a "these are > the issues" kind of thing. Ok, so I do have the diff that compiles, and it is 300 lines. Those will be extremely tricky 300 lines, but... > > I tried disabling CPU caches. Just like that, off, boom. My system > > will not survive that, and it looks like 100x slowdown. > > Yeah, no. That is not a realistic thing to do on any hardware since > the PPro, I'm afraid. What is special about PPro? Well -- cache off kind of is what I want -- kills Spectre _and_ Meltdown ;-), attacking close to the fundametal issue. And it really should be doable on UP system, right? I guess I should re-try with plain VGA console, not framebuffer. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html