[PATCH v2 3/3] lmb: consider EFI memory map

[Simon Glass]

Hi Heinrich,

On Wed, 11 Jan 2023 at 09:59, Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
>
>
> On 1/11/23 17:48, Simon Glass wrote:
> > Hi,
> >
> > On Wed, 11 Jan 2023 at 06:59, Tom Rini <trini at konsulko.com> wrote:
> >>
> >> On Wed, Jan 11, 2023 at 08:43:37AM +0100, Heinrich Schuchardt wrote:
> >>>
> >>>
> >>> On 1/11/23 01:15, Simon Glass wrote:
> >>>> Hi Heinrich,
> >>>>
> >>>> On Mon, 9 Jan 2023 at 13:53, Heinrich Schuchardt
> >>>> <heinrich.schuchardt at canonical.com> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 1/9/23 21:31, Simon Glass wrote:
> >>>>>> Hi Mark,
> >>>>>>
> >>>>>> On Mon, 9 Jan 2023 at 13:20, Mark Kettenis <mark.kettenis at xs4all.nl> wrote:
> >>>>>>>
> >>>>>>>> From: Simon Glass <sjg at chromium.org>
> >>>>>>>> Date: Mon, 9 Jan 2023 13:11:01 -0700
> >>>>>>>>
> >>>>>>>> Hi Heinrich,
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> We need to fix how EFI does addresses. It seems to use them as
> >>>>>>>> pointers but store them as u64 ?
> >>>>>
> >>>>> That is similar to what you have been doing with physical addresses.
> >>>>>
> >>>>>>>
> >>>>>>> They're defined to a 64-bit unsigned integer by the UEFI
> >>>>>>> specification, so you can't change it.
> >>>>>>
> >>>>>> I don't mean changing the spec, just changing the internal U-Boot
> >>>>>> implementation, which is very confusing. This confusion is spreading
> >>>>>> out, too.
> >>>>>>
> >>>>>> Regards,
> >>>>>> Simon
> >>>>>
> >>>>> The real interesting thing is how memory should be managed in U-Boot:
> >>>>>
> >>>>> I would prefer to create a shared global memory management on 4KiB page
> >>>>> level used both for EFI and the rest of U-Boot.
> >>>>
> >>>> Sounds good.
> >>>>
> >>>>>
> >>>>> What EFI adds to the requirements is that you need more than free
> >>>>> (EfiConventionalMemory) and used memory. EFI knows 16 different types of
> >>>>> memory usage (see enum efi_memory_type).
> >>>>
> >>>> That's a shame. How much of this is legacy and how much is useful?
> >>>>
> >>>>>
> >>>>> When loading a file (e.g. with the "load" command) this should lead to a
> >>>>> memory reservation. You should not be able to load a second file into an
> >>>>> overlapping memory area without releasing the allocated memory first.
> >>>>>
> >>>>> This would replace lmb which currently tries to recalculate available
> >>>>> memory ab initio again and again.
> >>>>>
> >>>>> With managed memory we should be able to get rid of all those constants
> >>>>> like $loadaddr, $fdt_addr_r, $kernel_addr_r, etc. and instead use a
> >>>>> register of named loaded files.
> >>>>
> >>>> This is where standard boot comes in, since it knows what it has
> >>>> loaded and has pointers to it.
> >>>>
> >>>> I see a future where we don't use these commands when we want to save
> >>>> space. It can save 300KB from the U-Boot size.
> >>>>
> >>>> But this really has to come later, since there is so much churn already!
> >>>>
> >>>> For now, please don't add EFI allocation into lmb..that is just odd.
> >>>
> >>> It is not odd but necessary. Without it the Odroid C2 does not boot but
> >>> crashes.
> >>
> >> It's not Odroid C2, it's anything that with the bad luck to relocate
> >> over the unprotected EFI structures.
> >
> > So can EFI use the lmb calls to reserve its memory? This patch is backwards.
>
> Simon, the EFI code can manage memory, LMB cannot.
>
> Every time something in U-Boot invokes LMB it recalculates reservations
> *ab initio*.
>
> You could use lib/efi_loader/efi_memory to replace LMB but not the other
> way round.
>
> We should discard LMB and replace it by proper memory management.

We have malloc() but in general this is not used (so far) except with
some parts of standard boot, and even there we are maintaining
compatibility with existing fdt_addr_r vars, etc.

So what is the plan for this?

Reviewed-by: Simon Glass <sjg at chromium.org>

Regards,
Simon