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lmb: Reinstate access to memory above ram_top

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Revert commit eb052cbb896f ("lmb: add and reserve memory above ram_top")
and commit 1a48b0be93d4 ("lmb: prohibit allocations above ram_top even from
same bank"). These are based on incorrect premise of the first commit, that
"U-Boot does not use memory above ram_top". While U-Boot itself indeed does
not and should not use memory above ram_top, user can perfectly well use
that memory from the U-Boot shell, for example to load content in there.

Currently, attempt to use that memory to load large image using TFTP ends
with "TFTP error: trying to overwrite reserved memory...". With this change
in place, the memory can be used again.

Fixes: eb052cbb896f ("lmb: add and reserve memory above ram_top")
Fixes: 1a48b0be93d4 ("lmb: prohibit allocations above ram_top even from same bank")
Reported-by: Yuya Hamamachi <yuya.hamamachi.sx@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
This commit is contained in:
Marek Vasut 2026-01-28 00:48:40 +01:00 committed by Tom Rini
parent dba21bf0b6
commit a3075db94d
1 changed files with 1 additions and 16 deletions
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17
lib/lmb.c
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@ -611,7 +611,6 @@ static __maybe_unused void lmb_reserve_common_spl(void)
static void lmb_add_memory(void)
{
int i;
phys_addr_t bank_end;
phys_size_t size;
u64 ram_top = gd->ram_top;
struct bd_info *bd = gd->bd;
@ -625,23 +624,9 @@ static void lmb_add_memory(void)
for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
size = bd->bi_dram[i].size;
bank_end = bd->bi_dram[i].start + size;
if (size) {
if (size)
lmb_add(bd->bi_dram[i].start, size);
/*
* Reserve memory above ram_top as
* no-overwrite so that it cannot be
* allocated
*/
if (bd->bi_dram[i].start >= ram_top)
lmb_reserve(bd->bi_dram[i].start, size,
LMB_NOOVERWRITE);
else if (bank_end > ram_top)
lmb_reserve(ram_top, bank_end - ram_top,
LMB_NOOVERWRITE);
}
}
}