On Wed, Nov 27, 2024 at 06:08:25AM -0700, Simon Glass wrote:
> Hi Caleb,
>
> On Tue, 26 Nov 2024 at 09:15, Caleb Connolly <caleb.conno...@linaro.org> 
> wrote:
> >
> > Hi Simon,
> >
> > On 26/11/2024 16:38, Simon Glass wrote:
> > > Hi Caleb,
> > >
> > > On Tue, 26 Nov 2024 at 05:22, Caleb Connolly <caleb.conno...@linaro.org> 
> > > wrote:
> > >>
> > >> Hi Simon,
> > >>
> > >> On 26/11/2024 01:32, Simon Glass wrote:
> > >>> Hi Caleb,
> > >>>
> > >>> On Sun, 24 Nov 2024 at 11:38, Caleb Connolly 
> > >>> <caleb.conno...@linaro.org> wrote:
> > >>>>
> > >>>> Currently the early malloc initialisation is done partially in
> > >>>> board_init_f_init_reserve() (on arm64 at least), which configures
> > >>>> gd->malloc_base. But it isn't actually usable until initf_malloc() is
> > >>>> called which doesn't happen until after fdtdec_setup().
> > >>>>
> > >>>> This causes problems in a few scenarios:
> > >>>>
> > >>>> 1. when using MULTI_DTB_FIT as this needs a working malloc (especially
> > >>>>    for compressed FIT).
> > >>>
> > >>> Hmmm, how does this work today?
> > >>
> > >> I honestly have no idea, I assume boards that make use of it do some
> > >> custom board_f.
> > >
> > > OK.
> > >
> > >>>
> > >>>> 2. Some platforms may need to allocate memory as part of memory map
> > >>>>    initialisation (e.g. Qualcomm will need this to parse the memory map
> > >>>>    from SMEM).
> > >>>
> > >>> That really needs to be tidied up. When does this fixup need to be
> > >>> done? I imagine it is somewhere prior to setup_dest_addr() ? Perhaps
> > >>
> > >> It's necessary in order to figure out gd->ram_base/ram_size. We do it in
> > >> board_fdt_blob_setup() so that we can support another use-case where
> > >> U-Boot has an internal FDT (which it should use) but the memory layout
> > >> is provided via an external FDT which is unavailable (although this
> > >> usecase isn't enabled upstream yet).
> > >>
> > >>> we could introduce an event to do 'memory map' stuff?
> > >>
> > >> We could, but considering that on most platforms the pre-relocation
> > >> malloc is fixed at build time and at a known location relative to U-Boot
> > >> there is no reason for us to arbitrary decide that some codepaths at the
> > >> start of board_f aren't allowed to use malloc().
> > >>
> > >> Just moving the malloc initialization earlier ensures malloc() is
> > >> consistently available and greatly simplifies things.
> > >
> > > I'd like to see a more generic solution to this problem...I think we
> > > discussed this before?
> >
> > I think so. I'm not sure I follow with "more generic solution"?
>
> Using an event to set the RAM location, rather than repurposing the
> FDT-setup function.
>
> > >
> > > To my eye it looks like if we called an event in setup_dest_addr() we
> > > could allow ram_base to be set.
> >
> > Right, it's possible/likely that we could clean up how mach-snapdragon
> > currently does memory parsing.
> >
> > I do think this patch would still be justified even if we ignore the
> > Qualcomm case.

Simon,

> It does put malloc() outside the purview of trace. There is always
> going to be a race between which subsystem wants to be first and we
> have certainly changed it several times. But until we have an actual
> need, I think it is better to wait.

IPQ platforms use CONFIG_MULTI_DTB_FIT and CONFIG_MULTI_DTB_FIT_GZIP.
The gzip decompressor allocates memory and faces this problem. Moving
initf_malloc(), above helps resolve this. Would that be considered as
a good justification to moving up initf_malloc()? Please advice.

Thanks
Varada

> > >> fwiw, I had another variation of this patch which dropped initf_malloc()
> > >> entirely and just set up gd->malloc_limit/malloc_ptr in
> > >> board_init_f_init_reserve() since that's where we set malloc_base
> > >> anyways. But after digging some more there seem to be quite a few other
> > >> entrypoints into U-Boot that don't go through
> > >> board_init_f_init_reserve() (e.g. sandbox, EFI app) and it seemed more
> > >> error prone to duplicate the implementation there.
> > >
> > > Fair enough.
> > >
> > > One more thing I notice in your board_fdt_blob_setup() implementation
> > > in arch/arm/mach-snapdragon/board.c :
> > >
> > > It seems to be using either an built-in or external devicetree. It
> > > seems that we should show this in dm_announce(), i.e. with the call to
> > > fdtdec_get_srcname() ?
> >
> > Yes, the way it's implemented currently assumes that if CONFIG_OF_BOARD
> > is set that we'd never use the built-in DT and mach-snapdragon doesn't
> > fit this assumption. It's not a high priority but for sure something I'd
> > like to see fixed.
>
> I'm not even sure that assumption is right, actually...
>
> [..]
>
> REgards,
> Simon

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