Re: [Xen-devel] Re: [PATCH] Fix __XEN_INTERFACE_VERSION__ old config breakage

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 7 Apr 2006, at 08:48, Magnus Damm wrote:

> > Does this lead to a kernel that actually works (e.g., can you sgut it
> > down without crashing)? I doubt it.
> I use a kernel config without CONFIG_XEN_INTERFACE_VERSION, and
> building and running dom0 on x86 (in qemu) seems ok to me.
I tried 'xm save' on such a domU and that doesn't work. The reason is 
that the kernel tree expects to be calling the new sched_op hypercall, 
but because the interface version gets defined to zero, it actually 
calls the old sched_op hypercall which takes different arguments. I 
also tried rebooting such a domU and that doesn't work (the guest is 
killed but not restarted) -- again because the old and new sched_op 
hypercall take their arguments in different ways.
These problems are somewhat hidden I suppose, since you can boot and 
run happily with the domain for the most part, but it illustrates that 
if a guest is defining an obviously interface version we should fail 
the build, not build some inconsistent combination of guest kernel and 
hypervisor interface!
 -- Keir


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