Le 05/06/2026 à 01:09, Tom Rini a écrit :
On Fri, Jun 05, 2026 at 12:31:10AM +0200, Marek Vasut wrote:
On 6/4/26 9:37 AM, Ilias Apalodimas wrote:
Currently, the bi_dram[] information is stored in the board info
structure (bd). Because bd is only valid after reserve_board(),
dram_init_banksize() must be called late in the initialization process.
This limitation is problematic, as it forces us to rely on a variety of
bespoke functions to determine board RAM, bank memory sizes, and other
early setup requirements.
By moving bi_dram[] into the global data (gd), we can run it earlier.
This is particularly convenient since boards define their own
dram_init_banksize() routines, which do not always rely on parsing
Device Tree (DT) memory nodes.
Additionally, U-Boot defaults to relocating to the top of the first memory
bank. While boards currently use custom functions to override this
behavior, having the DRAM bank information available earlier in gd makes
relocating to a different bank trivial and standardizes the process.
Regarding the BD, this is likely really old, but it seems BD might be passed
from U-Boot to Linux somehow ? See [1] and U-Boot
include/asm-generic/u-boot.h :
8 * NOTE: This header file defines an interface to U-Boot. Including
9 * this (unmodified) header file in another file is considered normal
10 * use of U-Boot, and does *not* fall under the heading of "derived
11 * work".
Are we certain we are not breaking ABI here ?
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/boot/ppcboot.h
I've added in Christophe as the maintainer of one of the active and in
some ways oldest (since MPC8xx is very old) PowerPC platforms we still
actively support. A tested-by on this series that also includes
verifying Linux still comes up would be much appreciated.
Traveling at the moment. I will try to give it a go in a couple weeks.
My suspicion is that anything DT-based shouldn't change here, and in
turn if you're doing modern U-Boot you're probably doing
not-extremely-ancient kernel and so DT based booting.
Linux receives a pointer to the device tree from U-boot, nothing else as
far as I know.
Christophe
