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

[Ilias Apalodimas]

Thanks Christophe

I've sent a v6 in the meanwhile, but this part remains unchanged

Thanks
Ilias

On Tue, Jun 9, 2026, 17:23 Christophe Leroy (CS GROUP) <chleroy at kernel.org>
wrote:

>
>
> 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
>