you can't avoid M mode on riscv, ever. There are several trap cases that will drop you in to M mode.
And M mode does not have paging, so it will always be using what x86 would call real memory addresses. Given that, the more I look at this, the more I want Plan 9 KVA do be 0->1<<60 or so, and UVA to be above that. I have not yet seen a reason this won't work. It's just not like an x86 :-) thanks Ron P.S. Richard, this is all your fault, your comment a few days ago got me to thinking. Always a bad idea :-) On Wed, Jan 7, 2026 at 5:46 AM Richard Miller <[email protected]> wrote: > <[email protected]>: > > M mode, for > > example, has no virtual addressing, and it would be useful (to say the > > least) to have kernel and M mode have a common set of addresses. > > Basic question: when would you use M mode? Doesn't the kernel normally > run entirely in Supervisor mode? Will the firmware on your platform even > allow Plan 9 to get into M mode? > ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/Tf6e0b1b3f80df821-Maacb4cc0a8b566370c93ba31 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
