[PATCH v5 1/7] treewide: move bi_dram[] from bd to gd

[Christophe Leroy (CS GROUP)]

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