From mboxrd@z Thu Jan 1 00:00:00 1970 From: bakul@bitblocks.com (Bakul Shah) Date: Wed, 3 Jan 2018 10:28:25 -0800 Subject: [TUHS] OT: critical Intel design flaw In-Reply-To: References: <20180103134358.3F16818C098@mercury.lcs.mit.edu> Message-ID: <483D45E8-9F95-4A8E-8F19-05D1CF1F7FEF@bitblocks.com> On Jan 3, 2018, at 9:46 AM, ron minnich 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).