On 15.07.2019 19:28, Andy Lutomirski wrote: > On Mon, Jul 15, 2019 at 9:34 AM Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote: >> >> Juergen Gross <jgross@xxxxxxxx> writes: >> >>> The long term plan has been to replace Xen PV guests by PVH. The first >>> victim of that plan are now 32-bit PV guests, as those are used only >>> rather seldom these days. Xen on x86 requires 64-bit support and with >>> Grub2 now supporting PVH officially since version 2.04 there is no >>> need to keep 32-bit PV guest support alive in the Linux kernel. >>> Additionally Meltdown mitigation is not available in the kernel running >>> as 32-bit PV guest, so dropping this mode makes sense from security >>> point of view, too. >> >> Normally we have a deprecation period for feature removals like this. >> You would make the kernel print a warning for some releases, and when >> no user complains you can then remove. If a user complains you can't. >> > > As I understand it, the kernel rules do allow changes like this even > if there's a complaint: this is a patch that removes what is > effectively hardware support. If the maintenance cost exceeds the > value, then removal is fair game. (Obviously we weight the value to > preserving compatibility quite highly, but in this case, Xen dropped > 32-bit hardware support a long time ago. If the Xen hypervisor says > that 32-bit PV guest support is deprecated, it's deprecated.) Since it was implied but not explicit from Andrew's reply, just to make it explicit: So far 32-bit PV guest support has not been deprecated in Xen itself. Jan _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
