From: Miod Vallat <miod@online.fr>
Subject: Re: km_alloc(9), UAREA and kv_pageable
To: Mark Kettenis <mark.kettenis@xs4all.nl>
Cc: Martin Pieuchot <mpi@grenadille.net>, tech@openbsd.org
Date: Mon, 21 Oct 2024 18:33:45 +0000

> Looks like amd64 is the only architecture that does that guardpage
> thing.  So I think this is fine.

On that topic, it would be nice for at least all 64-bit arches with
USPACE_ALIGN = 0, to always allocate UPAGES + 1 contiguous virtual pages
for the u area, UPAGES physical pages, and make the lowest page's
virtual address transation invalid.

This has been on my todo list for a very long time, but
ENOTENOUGHSPARETIME as usual. Maybe once I'm retired...