AWS Graviton2

[Colin Percival]

Matthias Gamsjager wrote:
> so in other ARM news. Finally the new AWS M6g instances are available for
> public.
> 
> And FreeBSD 12.1-STABLE r359985 is doing just fine on it.

FreeBSD 12.1-RELEASE should mostly work.  The known issues are:

1. When a instance "shutdown" request is made to the EC2 API, a signal is
sent to ARM64 EC2 instances via a PL061 controller -- which we don't have
a driver for.  As a result, FreeBSD doesn't respond to the shutdown request
and EC2 eventually forcibly halts the instance (with predictable results of
unclean filesystems etc).

There is a review open for a driver (code contribution from Amazon!) but
there will be other work needed as well: https://reviews.freebsd.org/D24065

2. When an EBS volume is attached to an EC2 instance, an ACPI Notify is sent
alerting the instance to the "hotplug" event.  We handle these on x86, but
right now we're not doing anything with these on arm64.

3. While FreeBSD boots on "normal" Graviton 2 instances, we don't currently
boot on "bare metal" instances.  Jared McNeill was able to make NetBSD work
on these but I'm not sure exactly what was involved except that the words
"PCIe host controller" come up.

I don't know nearly enough about these low-level architectural details to
work on these issues, but if anyone here is interested in working on them
I'll be happy to help however I can.

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid