[PATCH v3 02/15] lmb: add a flag to allow suppressing memory map change notification

[Simon Glass]

Hi Tom,

On Mon, 14 Oct 2024 at 09:02, Tom Rini <trini at konsulko.com> wrote:
>
> On Mon, Oct 14, 2024 at 12:26:02PM +0530, Sughosh Ganu wrote:
> > On Sun, 13 Oct 2024 at 23:21, Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Sun, Oct 13, 2024 at 04:25:09PM +0530, Sughosh Ganu wrote:
> > >
> > > > Add a flag LMB_NONOTIFY that can be passed to the LMB API's for
> > > > reserving memory. This will then result in no notification being sent
> > > > from the LMB module for the changes to the LMB's memory map.
> > > >
> > > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > >
> > > Can you please elaborate on what we need this flag for, for example what
> > > the valid situation for it is? We should be updating (or adding comments
> > > such that updates are automatic..) to doc/api/lmb.rst as well. Thanks.
> >
> > The flag is used to prevent notifying the EFI code about the change in
> > the LMB memory map when the alloc/free request originates in the EFI
> > memory module.
>
> Simon, this is the loop you referred to on IRC the other day, and
> instead you solve this with the flag about a point of cooperation?

Yes, that's right. I'd like to have EFI allocations confined to the
EFI area until efi_init_obj_list() is called, then have EFI add the
lmb reservations to its own table, then own memory-allocation from
then on.

Basically if we apply my series[1] first, it will remove the need for
this EFI call and the associated complexity. Most of this series will
still be needed though.

>
> > The EFI memory module adds the memory region to its
> > memory map as part of the alloc/free operation. The idea is that the
> > LMB module should notify EFI about changes to its memory map when
> > these changes are initiated from non-EFI consumers of memory.
>
> OK, so the first change is that since doc/api/lmb.rst is just a
> kerneldoc of include/lmb.h we need to add the flag here, and we need to
> first document LMB_NOOVERWRITE which is already undocumented. The next
> change is that at the end of the series, update the rst with some
> paragraphs about what and why, for clarity, after auditing include/lmb.h
> for other items that are missing kerneldoc comments. I am willing to
> make that second change a follow-up series, however.

Regards,
Simon

[1] https://patchwork.ozlabs.org/project/uboot/list/?series=427729