[PATCH v3 03/15] efi: memory: use the lmb API's for allocating and freeing memory

[Simon Glass]

Hi Tom,

On Mon, 14 Oct 2024 at 15:04, Tom Rini <trini at konsulko.com> wrote:
>
> On Mon, Oct 14, 2024 at 01:13:17PM -0600, Simon Glass wrote:
> > Hi Tom,
> >
> > On Mon, 14 Oct 2024 at 09:56, Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Mon, Oct 14, 2024 at 09:50:37AM -0600, Simon Glass wrote:
> > > > Hi Sughosh,
> > > >
> > > > On Sun, 13 Oct 2024 at 04:55, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > > >
> > > > > Use the LMB API's for allocating and freeing up memory. With this, the
> > > > > LMB module becomes the common backend for managing non U-Boot image
> > > > > memory that might be requested by other modules.
> > > > >
> > > > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > > > > ---
> > > > > Changes since V2:
> > > > > * Use map_to_sysmem() to get the user-visible address to be shared
> > > > >   with the lmb API's for sandbox.
> > > > >
> > > > >  lib/efi_loader/Kconfig      |  1 +
> > > > >  lib/efi_loader/efi_memory.c | 77 +++++++++++--------------------------
> > > > >  2 files changed, 24 insertions(+), 54 deletions(-)
> > > >
> > > > When efi_init_obj() is called, it should be able to add the lmb memory
> > > > to its own tables. There is no need to worry about lmb after that,
> > > > since no other images will be loaded, except under EFI's control. Then
> > > > perhaps you don't need this patch?
> > >
> > > But that's not true. The EFI application can return us to the U-Boot
> > > prompt.
> >
> > Can you finish that thought? What are you getting at?
>
> Your assumption is false. As Heinrich followed up with, there are plenty
> of common cases, including *env* where efi_init_obj() is called and then
> the user can still do whatever they like via bootm. There is a need to
> worry about it. Trying to make an artificial distinction here
> complicates matters. Much more so than adjusting our almost non-existent
> documentation about memory map / layout to say that this EFI related
> data *is* U-Boot.

Which assumption? That it can add the lmb memory to its tables? But
efi_init_obj() is called every time the EFI subsystem is used. That
immediately puts us into 'EFI' mode.

What is *env*? Once efi_init_obj() is called, we know we are booting
an EFI app, so it is OK to go outside the U-Boot region. It has to be,
since U-Boot can be told to allocate anything, under the control of
the EFI app. But when U-Boot is just happily running and not using the
EFI loader, we should not be doing this. That is my primary concern.

Regards,
Simon