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

[Randolph Sapp <rs@ti.com>]

On Thu Apr 16, 2026 at 9:37 AM CDT, Ilias Apalodimas wrote:
> Hi Randolph,
>
>
> On Mon, 13 Apr 2026 at 23:36, <rs@ti.com> wrote:
>>
>> From: Randolph Sapp <rs@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@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.

>>         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