Re: [PATCH] ptp: Add vDSO-style vmclock support

"Michael S. Tsirkin" <[email protected]> Fri, 26 Jul 2024 08:52:16 -0400
Newsgroups dev.linux.lists.virtio-dev,dev.linux.lists.virtualization,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-rtc,org.kernel.vger.netdev,org.nongnu.qemu-devel
Message-ID <[email protected]>
On Fri, Jul 26, 2024 at 09:35:51AM +0100, David Woodhouse wrote:
> But for this use case, we only need a memory region that the hypervisor
> can update. We don't need any of that complexity of gratuitously
> interrupting all the vCPUs just to ensure that none of them can be
> running userspace while one of them does an update for itself,
> potentially translating from one ABI to another. The hypervisor can
> just update the user-visible memory in place.

Looks like then your userspace is hypervisor specific, and that's a
problem because it's a one way street - there is no way for hypervisor
to know what does userspace need, so no way for hypervisor to know which
information to provide. No real way to fix bugs.

-- 
MST