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

[Heinrich Schuchardt]

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.

Best regards

Heinrich