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

[Heinrich Schuchardt]

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.

Best regards

Heinrich