Re: [PATCH v7 09/10] um: Add dummy implementation for IO memcpy/memset

From: Johannes Berg
Date: Tue Oct 01 2024 - 08:54:13 EST


On Mon, 2024-09-30 at 15:23 +0200, Julian Vetter wrote:
> The um arch is the only architecture that sets the config 'NO_IOMEM',
> yet drivers that use IO memory can be selected. In order to make these
> drivers happy we add a dummy implementation for memcpy_{from,to}io and
> memset_io functions.

Maybe I'm just not understanding this series, but how does this work
with lib/logic_iomem.c?

You're adding these inlines unconditionally, so if this included
logic_io.h, you should get symbol conflicts?

Also not sure these functions should/need to do anything at all, there's
no IO memory on ARCH=um in case of not having logic_io.h. Maybe even
BUG_ON() or something? It can't be reachable (under correct drivers)
since ioremap() always returns NULL (without logic_iomem).

I think Arnd also said that other architectures might want to use
logic_iomem, though I don't see any now.

johannes