Re: Urgent: NetBSD domUs will not start after Xen kernel update

[David Brownlee <abs%netbsd.org@localhost>]

On 23 October 2017 at 17:33, Manuel Bouyer <bouyer%antioche.eu.org@localhost> wrote:
> On Mon, Oct 23, 2017 at 05:14:10PM +0100, Stephen Borrill wrote:
>> Thanks for your quick reply. I can confirm that the following command gets
>> VMs booting again:
>> /opt/xensource/libexec/xen-cmdline --set-xen pv-linear-pt=true
>>
>> i.e.
>> # xl info | grep commandline
>> xen_commandline        : dom0_mem=752M,max:752M watchdog ucode=scan dom0_max_vcpus=4 crashkernel=128M@256M console=vga vga=mode-0x0311 pv-linear-pt=true
>>
>> However, while this is a useful workaround, it's not great going forward as
>> the command line may be modified when other hotfixes or upgrades happen (or,
>> of course, may not be under your administrative control). What's the roadmap
>> for fixing this in the NetBSD kernel?
>
> The x86 pmap makes heavy use of linear mappings, so it's not going to be
> "fixed" anytime soon (actually I consider it's a bug in Xen that it is
> disabled by default).

How complicated would it be to detect this case in a NetBSD DOM0 and
panic with an appropriate message, so users know what to adjust?