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Re: Kernel modules on 10.1



On Tue, 18 Mar 2025, Manuel Bouyer wrote:
On Tue, Mar 18, 2025 at 05:28:32PM +0000, Stephen Borrill wrote:
On Tue, 18 Mar 2025, Greg Troxel wrote:
Stephen Borrill <netbsd%precedence.co.uk@localhost> writes:

I would say it's a bug in 10 that *if* KDTRACE_HOOKS changes the module
ABI, that it isn't enabled in XEN3_DOMU.  Quick grepping makes me think
it's enabled there in current but not 10.

Yes, it looks like KDTRACE should be in all kernel configurations that
are ever likely to load the solaris module.

I wlil build and test and then submit a patch to be pulled up.

Sounds good.

However, on a netbsd-10 domU, modload zfs works ok.

It doesn't on a PV kernel, but it will with a GENERIC kernel running
as PVHVM.

Indeed, my 10 systems are pvhvm, both i386 and amd64, and I forgot about
that.

You have found a legit bug so I don't meant to say you shouldn't be
using PV, but I am curious what leads you to run PV instead of PVHVM.
I found that PVHVM was about twice as fast.

1) PVHVM wasn't an option before 10
2) All the existing VMs have disk layouts without a GPT or MBR, so no
bootloader (kernel loaded from domU root by XenServer using pygrub)
3) PVHVM breaks CDs (see other email from earlier), so you can't actually
install.

PVH would solve issues 2 and 3

Support for PVH is somewhat vague in the xapi toolstack (XenServer, XCP-ng). I have tried a NetBSD 10.1 PV VM that works on earlier versions on the latest XenServer 8.4. It fails to start in PV mode with the following error: Domain.Domain_build_pre_failed("Calling 'shadow_allocation_set 10 MiB' failed: Xenctrl.Error(\"22: Invalid argument\")")

I think this is because of the following change as part of the update to Xen 4.17:

- PV32, PV_LINEAR_PT and SHADOW_PAGING now compiled out

(from https://koji.xcp-ng.org/buildinfo?buildID=3568 )

It looks like you can set domain-type=pv-in-pvh on the VM (even it is only documented having pv and hvm values). This does attempt to start the VM, but it stops quickly afterwards. Perhaps this is because of PV_LINEAR_PT being removed or is this not relevant with PVH mode?

--
Stephen



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