[PATCH 04/16] event: add event to notify lmb memory map changes

[Ilias Apalodimas]

Hi Heinrich,

On Sat, 14 Sept 2024 at 18:08, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> On 9/5/24 10:27, Sughosh Ganu wrote:
> > Add an event which would be used for notifying changes in the
> > LMB modules' memory map. This is to be used for having a
> > synchronous view of the memory that is currently in use, and that is
> > available for allocations.
>
> The synchronous view problem only exists because we are duplicating
> data. Store the EFI memory type in LMB and the problem vanishes.

We could, but I wonder if that would be enough.
Apart from the EFI memory types, we plan on fixing the EFI memory
attributes. I'll go read the spec again and take look at EDK2 but
IIRC, you can't correlate memory types to memory attributes (at least
not for all of them).

If that's true we'll also need the attributes in LMB + perhaps logic
for 64kb page size OSes and 4KB page firmware, which might be a bit
too much. In that case, I think the sync is fine, but I really don't
see the point of making an event out of it. Perhaps we could just
update the efi memory map directly from LMB.

Thanks
/Ilias
>
> The event is only needed to notify EFI_EVENT_GROUP_MEMORY_MAP_CHANGE.
>
> Best regards
>
> Heinrich
>
> >
> > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > ---
> >   common/event.c  |  2 ++
> >   include/event.h | 14 ++++++++++++++
> >   2 files changed, 16 insertions(+)
> >
> > diff --git a/common/event.c b/common/event.c
> > index dda569d447..fc8002603c 100644
> > --- a/common/event.c
> > +++ b/common/event.c
> > @@ -48,6 +48,8 @@ const char *const type_name[] = {
> >
> >       /* main loop events */
> >       "main_loop",
> > +
> > +     "lmb_map_update",
> >   };
> >
> >   _Static_assert(ARRAY_SIZE(type_name) == EVT_COUNT, "event type_name size");
> > diff --git a/include/event.h b/include/event.h
> > index fb353ad623..fce7e96170 100644
> > --- a/include/event.h
> > +++ b/include/event.h
> > @@ -153,6 +153,14 @@ enum event_t {
> >        */
> >       EVT_MAIN_LOOP,
> >
> > +     /**
> > +      * @EVT_LMB_MAP_UPDATE:
> > +      * This event is triggered on an update to the LMB reserved memory
> > +      * region. This can be used to notify about any LMB memory allocation
> > +      * or freeing of memory having occurred.
> > +      */
> > +     EVT_LMB_MAP_UPDATE,
> > +
> >       /**
> >        * @EVT_COUNT:
> >        * This constants holds the maximum event number + 1 and is used when
> > @@ -203,6 +211,12 @@ union event_data {
> >               oftree tree;
> >               struct bootm_headers *images;
> >       } ft_fixup;
> > +
> > +     struct event_lmb_map_update {
> > +             u64 base;
> > +             u64 size;
> > +             u8 op;
> > +     } lmb_map;
> >   };
> >
> >   /**
>