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

Simon Glass sjg at chromium.org
Wed Jan 11 01:15:26 CET 2023


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.

Regards,
Simon


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