On Mon, Feb 10, 2020 at 02:13:19PM +0000, Marc Zyngier wrote: > KVM/arm was merged just over 7 years ago, and has lived a very quiet > life so far. It mostly works if you're prepared to deal with its > limitations, it has been a good prototype for the arm64 version, > but it suffers a few problems: > > - It is incomplete (no debug support, no PMU) > - It hasn't followed any of the architectural evolutions > - It has zero users (I don't count myself here) > - It is more and more getting in the way of new arm64 developments > > So here it is: unless someone screams and shows that they rely on > KVM/arm to be maintained upsteam, I'll remove 32bit host support > form the tree. One of the reasons that makes me confident nobody is > using it is that I never receive *any* bug report. Yes, it is perfect. > But if you depend on KVM/arm being available in mainline, please shout. It is only very recently that 64-bit ARM has really started to filter down to people like me, and people like me have setup systems which use 32-bit VMs under 64-bit hosts (about a year ago now.) In fact, everything that you presently see for the *.armlinux.org.uk domain now runs inside several 32-bit ARM VMs under a 64-bit ARM host. It isn't perfect; I've found issues with qemu and libvirt. One example is the rather sub-standard RTC implementation, which means if you use libvirt's managesave across a host reboot, the guests idea of time-of-day freezes while it's asleep, and resumes when the guest is reloaded - resulting in the guests time-of-day being rather wrong, sometimes to the point that NTP gives up. That becomes very painful if you use kerberos authentication, where time-of-day is important. So, just because you haven't received any bug reports doesn't mean there aren't any users; there certainly are, there are problems, but the problems are in places other than the kernel. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
