Date: Tue, 16 Apr 2013 08:27:47 -0600 From: "Justin T. Gibbs" <gibbs@FreeBSD.org> To: David Chisnall <theraven@FreeBSD.org> Cc: soc-status <soc-status@FreeBSD.org> Subject: =?utf-8?Q?Re=3A_Mentor_of_the_Project_=22PCI_frontend_XEN_PV_dri?= =?utf-8?Q?ver=22=EF=BC=9F?= Message-ID: <BB3632BC-9E6D-4190-A4DC-8361A60B45DB@FreeBSD.org> In-Reply-To: <5BDCBCBB-E65D-472E-B990-F1382A4BADF0@FreeBSD.org> References: <CAEQjb-RV30H9h8_tO%2BC0SkWAOi0DNF3G9xzpNFkj1_OKR%2ByLkw@mail.gmail.com> <920A79FE-8C56-4D26-8611-3CD48602FC3B@freebsd.org> <5BDCBCBB-E65D-472E-B990-F1382A4BADF0@FreeBSD.org>
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On Apr 12, 2013, at 1:21 AM, David Chisnall <theraven@FreeBSD.org> = wrote: > On 12 Apr 2013, at 05:13, "Justin T. Gibbs" <gibbs@freebsd.org> wrote: >=20 >> This particular project was proposed for last year's GSoC when both = attilio@FreeBSD.org and I were actively working on full Xen PV support = for FreeBSD. That project still continues, but at a slower pace due to = changing needs at our respective employers. Given the lack of maturity = of our Xen PV port, I think this would be a difficult project to attempt = at this time. >>=20 >> If you are interested in Xen and have access to x86 hardware with HVM = capabilities, writing a SCSI or USB PV frontend for FreeBSD is a better = project to select. FreeBSD's Xen HVM support is very robust and, unlike = the PCI frontend driver, these drivers can be developed using an HVM = guest. The resulting drivers should work equally well in full PV mode = (with perhaps a few minor tweaks) when it is better supported. >>=20 >> I will update the wiki sometime tomorrow with more information on Xen = projects that are appropriate for this year's GSoC. >=20 > Do we support PHV mode in Xen yet? If not, then this might be a good = GSoC project. Most of the effort - it uses the PV boot mechanism, but = then the HVM pmap and PV drivers (including event channels, no APIC = emulation). Unlike the PV mode, it won't require us to maintain two = i386 pmap implementations for the increasingly rare case of trying to = run FreeBSD VMs on CPUs without virtualisation support, and it doesn't = have the QEMU overhead in dom0 that HVM does (even when you're using = fully PV devices, you still need it to boot), and which causes hosting = providers to charge more for HVM. >=20 > David The last time I was really active in the Xen community (over a year = ago), PHV was still in heavy development. However, it is certainly = coming. Once Cherry has full PV working for us, we should certainly = start the process of supporting it. -- Justin=
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