[TUHS] OT: critical Intel design flaw

Bakul Shah bakul at bitblocks.com
Thu Jan 4 04:28:25 AEST 2018


On Jan 3, 2018, at 9:46 AM, ron minnich <rminnich at gmail.com> wrote:
> 
> The type of kernel is orthogonal to this particular design flaw from what I know. It's about how page tables are set up for user mode processes. I may be wrong but pretty much every Unix or Unix-like kernel (including Plan 9) follows the page table model Windows and Linux use: the ring 0 PTEs are present in the page table, even in user mode, and we count on the architecture to prevent ring 3 access to ring 0 memory. This is certainly the case on all the ones I've worked on. 
> 
> I don't think a microkernel would save you.

My point was simply that in a ukernel this arrangement doesn't buy
you much as the real "OS" is just another user level process. The
ukernel is basically just a message router. In Mill the message
routing itself is done in h/w (well, a portal call is more like
a call to a different protection domain in the same thread so no
need for marshalling/unmarshalling arguments).



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