Re: [PATCH 0 of 2] Support for Paging/Sharing on AMD

[Tim Deegan <tim@xen.org>]

At 18:41 +0200 on 29 Mar (1333046483), Olaf Hering wrote:
> On Thu, Mar 29, Tim Deegan wrote:
> 
> > At 18:01 +0200 on 29 Mar (1333044093), Olaf Hering wrote:
> > > On Thu, Mar 29, Tim Deegan wrote:
> > > 
> > > > That is, can we just drop this whole test?
> > > 
> > > I'm ok with removing the existing boot_cpu_data.x86_vendor test,
> > > check only hap_enabled() and return -ENODEV otherwise.
> > > 
> > > A recent change added need_iommu() check, this should be moved up into
> > > the -ENODEV case becasue -EXDEV is for PoD.
> > 
> > That seems strange -- why would 'no; this VM uses PoD' be different from
> > 'no; this VM uses the IOMMU'?
> 
> Its just a made-up return code to have a proper error message in
> xenpagings init function.

Uh, OK.  But when we're adding this iommu interlock, it seems better to
bundle it in with PoD as 'VM is using an incompatible feature'.

> > I'll take a patch to change the return code if it also documents it in
> > the hypercall interface. :)
> 
> Where is it documented?

In the public headers (but basically not documented at all, even there).
There is some markup language (see, e.g. public/xen.h) that is used to
generate separate documentation, but public/domctl.h doesn't seem to
have any of that yet.

Tim.