On Mon, Jul 2, 2012 at 5:24 PM, Ian Campbell
<Ian.Campbell@xxxxxxxxxx> wrote:
On Mon, 2012-07-02 at 17:12 +0100, Adrian Shaw wrote:
>
> > e.g. /local/domain/16
>
> Where are you getting this path from at runtime?
>
> Using xs_get_domain_path
Doh, yeah ;-)
Where do you get the domid from?
Sorry :-P using xenbus_get_self_id()
>
> Is it just /local/domain/<domid> or subkeys under it too e.g.
> can you
> read /local/domain/<domid>/vm or /local/domain/<domid>/name?
>
>
> I have tried to write subkeys too, however I'm not sure whether I was
> doing so correctly. It yields the same error code.
Those ones are read-only. I know that xl creates a writable area
as /l/d/<domid>/data but I don't know about xend.
> There is no xs_mkdir implementation in Mini-OS, strangely.
I expect noone ever needed it yet, should be easy to add if you want.
As you may have gathered, I don't have the confidence or expertise to write it, but perhaps one day :-)
>
> How are you loading the domain?
>
> Using xm create mystub.config -c, unless you mean something more
> specific?
> Is there anything about permissions I should be placing in the
> configuration file?
Nope, it should all Just Work in this regard.
>
> "xenstore-ls -fp" should give you some insight into the
> permissions
> which are being set.
>
>
> I have tried that already, but couldn't find anything that explains
> what n0 or r0 mean?
http://wiki.xen.org/wiki/XenBus#Permissions has a bit on the (mad)
permission scheme.
It uses Python syntax though. n == no permissions, r == read only, w ==
write only, b == both. The number is the domain. The quirk is that the
first entry in the list is the owner and the permissions for all *other*
users (unless overridden further down the list)
Thanks for clearing that up, noted.
Clear as mud I expect...
BY way of an example:
/local/domain/1 = "" (n0,r1)
Means that domain 0 owns this path and can therefore read and write and
nobody else has any read or write privilege (the "n0" means this),
except domain 1 who can read it (the "r1"). So it seems that it is
expected that a domain cannot write /local/domain/<domid>, but it ought
to be able to read it.
> I wouldn't be surprised if a domain could not write
> to /local/domain/<domid> itself but there should be accessible
> keys
> under there.
>
>
> How can I browse these available keys at runtime?
xenstore-ls on the cmd line or xs_directory().
Many thanks Ian, I'll give that a shot. Could not figure out what that function was for.
Ian.
