Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap_resource'

[Richard Weinberger <richard@nod.at>]

Am 17.07.2014 12:28, schrieb Arnd Bergmann:
> On Thursday 17 July 2014 11:26:57 Richard Weinberger wrote:
>> Am 17.07.2014 11:20, schrieb Arnd Bergmann:
>>> On Thursday 17 July 2014 09:27:58 Chen Gang wrote:
>>>>                                          gfp_t gfp_mask, unsigned int order);
>>>>  extern void devm_free_pages(struct device *dev, unsigned long addr);
>>>>  
>>>> +#ifdef CONFIG_HAS_IOMEM
>>>>  void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res);
>>>> +#elif defined(CONFIG_COMPILE_TEST)
>>>> +static inline void __iomem *devm_ioremap_resource(struct device *dev,
>>>> +                                               struct resource *res)
>>>> +{
>>>> +       pr_warn("no hardware io memory, only for COMPILE_TEST\n");
>>>> +       return (__force void __iomem *)ERR_PTR(-ENXIO);
>>>> +}
>>>> +#endif /* CONFIG_HAS_IOMEM || CONFIG_COMPILE_TEST */
>>>>  
>>>>  /* allows to add/remove a custom action to devres stack */
>>>
>>> To be honest, I think it's a bad idea to introduce wrappers functions
>>> that are only available when CONFIG_COMPILE_TEST is set.
>>>
>>> COMPILE_TEST is a great tool in general, but it has its limits.
>>> In particular, the case for !CONFIG_IOMEM is completely obscure
>>> and we won't find any bugs by allowing more drivers to be built
>>> in those configurations, but attempting to do it would cause
>>> endless churn by changing each instance of 'depends on HAS_IOMEM'
>>> to 'depends on HAS_IOMEM || COMPILE_TEST'.
>>>
>>> Note that s390 no has gained support for IOMEM, tile has it most
>>> of the time (when PCI is enabled, so you get it in half the
>>> test builds already), score should set HAS_IOMEM and doesn't
>>> even have public compilers, and uml doesn't even compile in
>>> latest mainline. Nothing else ever sets NO_IOMEM.
>>
>> Huh? UML (v3.16-rc5-143-gb6603fe) builds fine here. What build issue are you facing?
> 
> This is what I got upon trying earlier. I have not attempted to look into
> why this is happening. Note this is on linux-next from yesterday,
> not mainline as I incorrectly stated above.
> 
> In file included from ../arch/um/include/asm/fixmap.h:58:0,
>                  from ../arch/um/include/asm/pgtable.h:11,
>                  from ../include/linux/mm.h:51,
>                  from ../kernel/uid16.c:6:
> ../include/asm-generic/fixmap.h: In function 'fix_to_virt':
> ../include/asm-generic/fixmap.h:31:2: error: size of unnamed array is negative
>   BUILD_BUG_ON(idx >= __end_of_fixed_addresses);

So, this is next-20140716?
I don't see the fixmap issue you're reporting, also not on the most recent next.

All I see is the known ext4 issue with CONFIG_SMP=n:

fs/ext4/super.c: In function ‘ext4_commit_super’:
fs/ext4/super.c:4547:41: error: ‘struct percpu_counter’ has no member named ‘counters’
  if (EXT4_SB(sb)->s_freeclusters_counter.counters)
                                         ^
fs/ext4/super.c:4551:39: error: ‘struct percpu_counter’ has no member named ‘counters’
  if (EXT4_SB(sb)->s_freeinodes_counter.counters)

Thanks,
//richard