[PATCH v2 14/32] lmb: introduce a function to add memory to the lmb memory map

[Sughosh Ganu]

On Wed, 21 Aug 2024 at 07:41, Simon Glass <sjg at chromium.org> wrote:
>
> Hi Sughosh,
>
> On Tue, 20 Aug 2024 at 02:17, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> >
> > On Fri, 16 Aug 2024 at 02:04, Simon Glass <sjg at chromium.org> wrote:
> > >
> > > Hi Sughosh,
> > >
> > > On Wed, 14 Aug 2024 at 12:01, Sughosh Ganu <sughosh.ganu at linaro.org> wrote:
> > > >
> > > > Introduce a function lmb_add_memory() to add available memory to the
> > > > LMB memory map. Call this function during board init once the LMB data
> > > > structures have been initialised.
> > > >
> > > > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > > > ---
> > > > Changes since V1:
> > > > * Call the lmb_add_memory() from lmb_init() instead of
> > > >   lmb_mem_regions_init().
> > > >
> > > >
> > > >  include/lmb.h | 10 ++++++++++
> > > >  lib/lmb.c     | 42 ++++++++++++++++++++++++++++++++++++++++++
> > > >  2 files changed, 52 insertions(+)
> > > >
> > >
> > > Reviewed-by: Simon Glass <sjg at chromium.org>
> > >
> > > But this should not be weak.
> >
> > This is being made weak, as there would be lmb_add_memory()
> > definitions added for powerpc and x86 arch's in the EFI part of my
> > patches. Moreover, the lmb_add_memory() function would be called even
> > in the SPL stage when LMB is enabled for that stage. So I am not sure
> > how do we get around this. You can check the relevant branch [1] on my
> > github to check for the specific commits [2][3] that I am referring
> > to. Thanks.
>
> This is really strange.
>
> The e820 is different on each x86 board. I'm not sure we want that in
> the lmb. What is the purpose of that? It is somewhat circular in most
> cases, since U-Boot sets it up itself. Where it comes from coreboot,
> it looks like we are mirroring it in the EFI memory map. I'm not sure
> I understand all this very well.

Yes, me neither. And I want to keep the behaviour same as before the
patches. You would know that the function efi_add_known_memory() gets
the memory map from a function install_e820_map() which includes
conventional memory, which is the ram memory. And I am basically now
doing this as part of the lmb_add_memory() function instead. Are you
sure that we can do away with this function, and instead use the
ram_base and ram_top values from the global data structure instead? I
believe you have boards which exercise this code? So it will be great
if you can test this if I remove the function for the e820 module.

>
> For fsl, perhaps copy the #ifdef and handle arch.resv_ram in your code?

This is for adding ram to the lmb memory map, but yes, I can check by
putting an ifdef in the function. Although the function might look
ugly and hackish. Thanks.

-sughosh

>
> [..]
> Regards,
> Simon
>
>
> > [1] - https://github.com/sughoshg/u-boot/tree/lmb_efi_sep_apis_nrfc_next_v3
> > [2] - https://github.com/u-boot/u-boot/commit/077ced7aaa6d495b1b87b324fb1c60658c203ce1
> > [3] - https://github.com/u-boot/u-boot/commit/d0fa3a89865b796f3bbebffebbe4f7b5b048c140
> >