Re: [PATCH] of/address: Drop ISA parts when !CONFIG_ISA

[Daniel Palmer]

Hi Daniel, (Replying to myself..)

On Sat, 27 Jun 2026 at 02:19, Daniel Palmer <daniel@xxxxxxxxx> wrote:
>
> The PCI parts are already wrapped in #ifdef CONFIG_PCI
> so it seems sensible to add #ifdef CONFIG_ISA around the ISA
> parts.
>
> This reduces the code/data size a bit on configs with !CONFIG_ISA.
>
> Signed-off-by: Daniel Palmer <daniel@xxxxxxxxx>
> ---
>
> Sorry for the spam, somehow I botched sending a patch..
>
> I thought about making this RFC as I'm a bit unsure if machines
> that need this ISA stuff actually select CONFIG_ISA or not.

So sashiko worked out what is going on here. A few machines have
things connected via an LPC bus that is derived from ISA and needs the
code to parse those nodes but those machines don't select CONFIG_ISA.
There seem to be ~15 devicetrees in total that actually need it (1 in
x86, 1 in arm64, a few in mips/loongson for loongson machines, and
then a few in ppc).

I made a series that adds CONFIG_OF_ISA to enable this code, selects
it in the places that needs it, and then does the original part of
disabling the code if not needed. I will wait a bit before sending.
The reason to do this is I am using devicetree to boot a machine with
4MB of RAM and a 7MHz CPU. Removing dead code/data like this helps.

Cheers!