Re: [PATCH] um: Turn HAS_IOPORT_MAP off

["Tiwei Bie" <tiwei.btw@antgroup.com>]

On 2025/7/2 21:39, Arnd Bergmann wrote:
> On Wed, Jul 2, 2025, at 15:02, Tiwei Bie wrote:
>> On 2025/7/2 19:09, Arnd Bergmann wrote:
>>> On Tue, Jul 1, 2025, at 14:22, Tiwei Bie wrote:
>>> xtensa selects NO_IOPORT_MAP, which means that HAS_IOPORT_MAP
>>> gets disabled here:
>>>
>>> arch/xtensa/Kconfig:config NO_IOPORT_MAP
>>> arch/xtensa/Kconfig-    def_bool n
>>
>> The value of NO_IOPORT_MAP on xtensa is inverted compared to that
>> on most other platforms that explicitly defines NO_IOPORT_MAP.
> 
> Ah of course, sorry for misunderstanding. Apparently this only
> existed because it was selected by a long gone platform:
> 
> -config XTENSA_PLATFORM_S6105
> -       bool "S6105"
> -       select HAVE_IDE
> -       select SERIAL_CONSOLE
> -       select NO_IOPORT_MAP

Cool, that makes sense!

> 
> Before commits
> 
> d38efc1f150f ("xtensa: adopt generic io routines")
> d046f77ec4a4 ("xtensa: set NO_IOPORT to 'n' by default")
> 
> it was always-on, and I think the idea at the time was to
> make it behave more like the generic PCI code, while it
> was originally copied from sparc, which does things quite
> differently.
> 
> It is rather clear that the I/O port implementation on
> xtensa never actually worked, and some of the comments
> on its PCI code suggest that it was never really used
> either.

Thanks for the details. I'm not really familiar with xtensa;
my understanding comes merely from reading the code. Please
feel free to proceed with your patch. I also think it is a
more generic solution. :)

Regards,
Tiwei