[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] xentrace, arm, hvm

On 08/02/14 15:51, Pavlo Suikov wrote:

Hi Pavlo,

>  > To support xentrace on ARM, we will need at least:
> I would readily do that if you give me some directions on where to look
> at, or a high-level explanation of:
>  > - to replace rcu_lock_domain_by_any_id() by a a similar function
> What semantics should this function have?

I would copy in part get_pg_owner (arch/x86/mm/mm.c) in the ARM code.
The check "unlikely(paging_mode_translate(curr))" will always fail on ARM.

Probably best just todig in and ask questions as issues arise.

After making a quick workaround to rcu_lock DOMAIN_XEN on arm (in the
quite same manner it is done in x86) I've faced different problem.
Specifically, p2m_lookup for an address in the xen restricted heap fails
on the very first map call: p2m_map_first returns zero page due to both
p2m->first_level and p2m_first_level_index(addr) equal to zero. As far
as I understand xen simply does not know how to make p2m translation for
it's own restricted heap on arm. Am I right?

For DOMID_XEN, the p2m is not initialized. When xentrace requests to map a page by directly giving the mfn (machine frame number), so there is no need of translation.

I would either add a specific case for DOMID_XEN in get_page_from_gfn or p2m_lookup.


Julien Grall

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.