On Sun, 13 Feb 2022 at 10:22, Marc Zyngier <maz@xxxxxxxxxx> wrote: > > [+ Alex for HVF] > > On Sun, 13 Feb 2022 05:05:33 +0000, > Akihiko Odaki <akihiko.odaki@xxxxxxxxx> wrote: > > Hi, > > This breaks in a case where highmem is disabled but can have more than > > 4 GiB of RAM. M1 (Apple Silicon) actually can have 36-bit PA with HVF, > > which is not enough for highmem MMIO but is enough to contain 32 GiB > > of RAM. > > Funny. The whole point of this series is to make it all work correctly > on M1. > > > Where the magic number of 4 GiB / 32-bit came from? > > Not exactly a magic number. From QEMU's docs/system/arm/virt.rst: > > <quote> > highmem > Set ``on``/``off`` to enable/disable placing devices and RAM in physical > address space above 32 bits. The default is ``on`` for machine types > later than ``virt-2.12``. > </quote> > > TL;DR: Removing the bogus 'highmem=off' option from your command-line > should get you going with large memory spaces, up to the IPA limit. Yep. I've tested this with hvf, and we now correctly: * refuse to put RAM above 32-bits if you asked for a 32-bit IPA space with highmem=off * use the full 36-bit address space if you don't say highmem=off on an M1 Note that there is a macos bug where if you don't say highmem=off on an M1 Pro then you'll get a macos kernel panic. M1 non-Pro is fine. thanks -- PMM _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
