linux-kernel - Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for 'devm_ioremap

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Date:	Thu, 17 Jul 2014 19:32:41 +0800
From:	Chen Gang <gang.chen.5i5j@...il.com>
To:	Richard Weinberger <richard@....at>, Arnd Bergmann <arnd@...db.de>
CC:	Guenter Roeck <linux@...ck-us.net>,
	Lars-Peter Clausen <lars@...afoo.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	dmitry.torokhov@...il.com, linux-iio@...r.kernel.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>, teg@...m.no,
	Thierry Reding <thierry.reding@...il.com>,
	Lennox Wu <lennox.wu@...il.com>, Marek Vasut <marex@...x.de>,
	Liqin Chen <liqin.linux@...il.com>, msalter@...hat.com,
	linux-pwm@...r.kernel.org, devel@...verdev.osuosl.org,
	linux-watchdog@...r.kernel.org, linux-input@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	knaack.h@....de, Martin Schwidefsky <schwidefsky@...ibm.com>,
	Mischa.Jonker@...opsys.com, jic23@...nel.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: Re: [PATCH] drivers: Let several drivers depends on HAS_IOMEM for
 'devm_ioremap_resource'



On 07/17/2014 06:58 PM, Richard Weinberger wrote:
> 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)
> 

Yeah, and I have notified to ext4 related maintainer, yesterday, and he
has already send fix patch for it, I guess it will be integrated into
main line soon.


Thanks.
-- 
Chen Gang

Open, share, and attitude like air, water, and life which God blessed
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