Re: PVH: libxl expertise...

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Tue, 13 Nov 2012 10:00:53 +0000
Ian Campbell <Ian.Campbell@citrix.com> wrote:

> On Tue, 2012-11-13 at 03:09 +0000, Mukesh Rathor wrote:
> > Hi,
> > 
> > I am wondering if there's libxl expert who can help me make some PVH
> > related changes to libxl, pref in the US time zone. I could consult
> > on irc or the phone.
> 
> I think most of the libxl experts are in European time zones. Probably
> the best bet is to just ask your questions either here or on IRC.

For PVH, xc_dom_feature_translated is not returning true, looks like
its not finding XENFEAT_auto_translated_physmap set in the elf???

I've modified the arch/x86/xen/xen-head.S file to include the PVH:

ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .asciz "!writable_page_tables|pae_pgdir_above_4gb"FEATURES_PVH)

where
#define FEATURES_PVH "|writable_descriptor_tables" \
                    "|auto_translated_physmap" \
                    "|supervisor_mode_kernel" \
                    "|hvm_callback_vector"


So, not sure why it's failing. In xc_dom_parse_image(), I see 
dom->parms.f_required is 0. I assume this is what the kernel is built
with and should be filled with the values above? Presumably, 
dom->f_requested is what the library expects the kernel to have. 
I set it as:

libxl__build_pv():
    if (is_pvh) {
        printf("info..features:%s\n", info->u.pv.features);
        info->u.pv.features = strdup("auto_translated_physmap");
    }

which is temporary hack, and I wanna consult with libxl expert for the
proper way to to this. I don't see any thing similar being done.

I can't tell why f_active is there. I also see supported, may be thats
the string of what the kernel supports. It is set to 0x11 ??? 

Hmm... Using readelf and hexeditor, I see the feature string properly
set in vmlinux (assume its in bzImage too). So, not sure whats going on.

thanks
Mukesh