Re: Kexec and libxenctlr.so

[Julien Grall <julien@xxxxxxx>]

Hi,

On 11/06/2020 16:21, Jürgen Groß wrote:
> On 11.06.20 16:57, Julien Grall wrote:
> > Hi all,
> >
> > kexec-tools has an option to load dynamically libxenctlr.so (not 
> > .so.4.x) (see [1]).
> > Given that the library has never been considered stable, it is 
> > probably a disaster that is waiting to happen.
> > Looking at the tree kexec is using the follow libxc functions:
> >     - xc_kexec_get_range()
> >     - xc_kexec_load()
> >     - xc_kexec_unload()
> >     - xc_kexec_status()
> >     - xc_kexec_exec()
> >     - xc_version()
> >     - xc_interface_open()
> >     - xc_interface_close()
> >     - xc_get_max_cpus()
> >     - xc_get_machine_memory_map()
> >
> > I think it is uncontroversial that we want a new stable library for 
> > all the xc_kexec_* functions (maybe libxenexec)?
> > However I am not entirely sure where to put the others.
> >
> > I am thinking to introduce libxensysctl for xc_get_max_cpus() as it is 
> > a XEN_SYSCTL. We could possibly include xc_get_machine_memory_map() 
> > (despite it is a XENMEM_).
> > For xc_version(), I am thinking to extend libxentoolcore to also 
> > include "stable xen API".
> > Any opinion on the approach?
> You could consider hypfs (at least for some of the functionality).
That would work!

> xc_version() and xc_get_max_cpus() would be rather easy.
I am guessing we will need a fallback to the normal hypercalls if hypfs 
is not present.
> xc_get_machine_memory_map() is using a stable hypercall used by
> the kernel, too.
IIUC, you are suggesting to put this one in hypfs library as well. Is 
that correct?
Thank you for the input!

Cheers,

--
Julien Grall