[PATCHv3 6/6] memory: reserve from start_addr_sp to end_addr_sp

[Randolph Sapp]

On Thu Apr 16, 2026 at 2:01 PM CDT, Randolph Sapp wrote:
> On Thu Apr 16, 2026 at 9:37 AM CDT, Ilias Apalodimas wrote:
>> Hi Randolph,
>>
>>
>> On Mon, 13 Apr 2026 at 23:36, <rs at ti.com> wrote:
>>>
>>> From: Randolph Sapp <rs at ti.com>
>>>
>>> Add a new global data struct member called end_addr_sp. This stores the
>>> original value of relocaddr, directly from setup_dest_addr. This is
>>> specifically to avoid any adjustments made by other init functions.
>>>
>>> Reserve the memory from gd->start_addr_sp - CONFIG_STACK_SIZE to
>>> gd->end_addr_sp instead of gd->ram_top. This allows platform specific
>>> relocation addresses to work without unnecessarily painting over a large
>>> range.
>>>
>>
>> Is there a platform we can test the changes? Running the in QEMU had
>> no differences.
>
> Not yet. This is a mandatory requirement for pocketbeagle2, but otherwise the
> default behavior is the same as it ever was.
>
> You can change the relocation address in the function you snipped out below to
> an arbitrary value for testing.
>
>>> Signed-off-by: Randolph Sapp <rs at ti.com>
>>> ---
>>
>> [...]
>>
>>>  #ifdef CFG_PRAM
>>> diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
>>> index 745d2c3a966..2f3ef26a17c 100644
>>> --- a/include/asm-generic/global_data.h
>>> +++ b/include/asm-generic/global_data.h
>>> @@ -115,6 +115,12 @@ struct global_data {
>>>          * @start_addr_sp: initial stack pointer address
>>>          */
>>>         unsigned long start_addr_sp;
>>> +       /**
>>> +        * @end_addr_sp: the end of memory currently in use by uboot,
>>> +        *               should be the original value of the relocaddr before
>>> +        *               any other allocations shift it
>>> +        */
>>> +       unsigned long end_addr_sp;
>>>         /**
>>>          * @reloc_off: relocation offset
>>>          */
>>> diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
>>> index b3b292ebf56..bd0d875a8cd 100644
>>> --- a/lib/efi_loader/efi_memory.c
>>> +++ b/lib/efi_loader/efi_memory.c
>>> @@ -870,8 +870,8 @@ static void add_u_boot_and_runtime(void)
>>>         /* Add U-Boot */
>>>         uboot_start = ((uintptr_t)map_sysmem(gd->start_addr_sp, 0) -
>>>                        uboot_stack_size) & ~EFI_PAGE_MASK;
>>> -       uboot_pages = ((uintptr_t)map_sysmem(gd->ram_top - 1, 0) -
>>> -                      uboot_start + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
>>> +       uboot_pages = ((gd->end_addr_sp - uboot_start) + EFI_PAGE_MASK) >>
>>> +                     EFI_PAGE_SHIFT;
>>
>> The map_sysmem dance is still needed here for sandbox.
>>
>
> Why? We're not using that address directly. We're just trying to figure out how
> large the carveout region is.
>
> There's not anything funky going on with the global data structure for sandbox
> functionality is there? LMB definitely didn't do anything to account for that.

Ah. Symmetry, to answer my own question. We *may* get a virtual address.

That does bring up another issue though. What good does reserving a virtual
region that simply maps to a physical region do? Shouldn't we reserve the
physical region outright? Isn't that what LMB is tracking?

Suppose I need to read up on this sandbox and architecture dependent virtual
addressing scheme.

>>>         efi_update_memory_map(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
>>>                               false, false);
>>>  #if defined(__aarch64__)
>>> diff --git a/lib/lmb.c b/lib/lmb.c
>>> index 7ecc548d831..da61b005154 100644
>>> --- a/lib/lmb.c
>>> +++ b/lib/lmb.c
>>> @@ -534,46 +534,19 @@ static long lmb_reserve(phys_addr_t base, phys_size_t size, u32 flags)
>>>
>>>  static void lmb_reserve_uboot_region(void)
>>>  {
>>> -       int bank;
>>> -       ulong end, bank_end;
>>> +       ulong size;
>>>         phys_addr_t rsv_start;
>>> -       ulong pram = 0;
>>>
>>>         rsv_start = gd->start_addr_sp - CONFIG_STACK_SIZE;
>>> -       end = gd->ram_top;
>>> +       size = gd->end_addr_sp - rsv_start;
>>>
>>> -       /*
>>> -        * Reserve memory from aligned address below the bottom of U-Boot stack
>>> -        * until end of RAM area to prevent LMB from overwriting that memory.
>>> -        */
>>> -       debug("## Current stack ends at 0x%08lx ", (ulong)rsv_start);
>>> -
>>> -#ifdef CFG_PRAM
>>> -       pram = env_get_ulong("pram", 10, CFG_PRAM);
>>> -       pram = pram << 10; /* size is in kB */
>>> -#endif
>>
>> This functionality is removed, but we still have boards defining CFG_PRAM
>
> The PRAM allocation occurs before this, and it is carved out of the region
> covered by start_addr_sp through end_addr_sp. It's actually part of the reason I
> needed to add end_addr_sp, as it moves the relocation address pointer. We don't
> need to account for it separately now.
>
>>> +       debug("## Current stack ends at 0x%08lx\n", (ulong)rsv_start);
>>>
>>> -       for (bank = 0; bank < CONFIG_NR_DRAM_BANKS; bank++) {
>>> -               if (!gd->bd->bi_dram[bank].size ||
>>> -                   rsv_start < gd->bd->bi_dram[bank].start)
>>> -                       continue;
>>> -               /* Watch out for RAM at end of address space! */
>>> -               bank_end = gd->bd->bi_dram[bank].start +
>>> -                       gd->bd->bi_dram[bank].size - 1;
>>> -               if (rsv_start > bank_end)
>>> -                       continue;
>>> -               if (bank_end > end)
>>> -                       bank_end = end - 1;
>>> -
>>> -               lmb_reserve(rsv_start, bank_end - rsv_start - pram + 1,
>>> +       if (gd->flags & GD_FLG_SKIP_RELOC)
>>> +               lmb_reserve((phys_addr_t)(uintptr_t)_start, gd->mon_len,
>>>                             LMB_NOOVERWRITE);
>>> -
>>> -               if (gd->flags & GD_FLG_SKIP_RELOC)
>>> -                       lmb_reserve((phys_addr_t)(uintptr_t)_start,
>>> -                                   gd->mon_len, LMB_NOOVERWRITE);
>>> -
>>> -               break;
>>> -       }
>>> +       else
>>> +               lmb_reserve(rsv_start, size, LMB_NOOVERWRITE);
>>>  }
>>>
>>>  static void lmb_reserve_common(void *fdt_blob)
>>> --
>>> 2.53.0
>>>
>>
>> Thanks
>> /Ilias