linux-kernel - Re: [PATCH] include/asm-generic/io.h: add dummy fuctions to support 'COMPILE

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Date:	Thu, 04 Jul 2013 14:35:19 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	Steven Rostedt <rostedt@...dmis.org>,
	Arnd Bergmann <arnd@...db.de>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Richard Weinberger <richard@....at>,
	Jeff Dike <jdike@...toit.com>,
	David Sharp <dhsharp@...gle.com>,
	"sfr@...b.auug.org.au" <sfr@...b.auug.org.au>,
	Ingo Molnar <mingo@...nel.org>,
	uml-devel <user-mode-linux-devel@...ts.sourceforge.net>,
	uml-user <user-mode-linux-user@...ts.sourceforge.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-Arch <linux-arch@...r.kernel.org>,
	Mark Brown <broonie@...nel.org>,
	David Miller <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Kosina <trivial@...nel.org>, Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH] include/asm-generic/io.h: add dummy fuctions to support
 'COMPILE_TEST' in 'asm-generic'.

On 07/04/2013 02:12 PM, Greg KH wrote:
> On Thu, Jul 04, 2013 at 12:50:31PM +0800, Chen Gang wrote:
>> On 07/04/2013 12:08 PM, Greg KH wrote:
>>>>> config COMPILE_TEST
>>>>>        bool "Compile also drivers which will not load"
>>>>>        default n
>>> This has _nothing_ to do with asm-generic, sorry.  Please don't confuse
>>> the issue.
>>
>> But when I choose allmodconfig, then "COMPILE_TEST=y". this may allow a
>> module to compile under the architectures which no related HW support.
>>
>> When cause compiling issue (HW not support), it is not module's issue,
>> we can not 'fix' module by force, and it is not architecture's issue,
>> either.
>>
>> So we have to look for who has duty for this issue. At least now, it
>> seems only 'asm-generic' can be qualified to play this unlucky role.
> 
> You seem to not understand what asm-generic is, or does, or I still do
> not understand what you are proposing.
> 

Maybe both/neither of us.  :-)

> Please send a patch showing what you are trying to do here, so that we
> can properly understand.
> 

Please help to check the patch below, thanks.

--------------------------patch begin----------------------------------

'asm-generic' need provide necessary configuration checking, if can't
pass checking, 'asm-generic' shouldn't implement it.

For 'COMPILE_TEST', according to its help contents, 'asm-generic' need
let it pass configuration checking, and provide related dummy contents
for it.

Part of 'COMPLE_TEST' help contents in "init/Kconfig":

  "...Despite they cannot be loaded there (or even when they load they cannot be used due to missing HW support)..."

One sample for using 'COMPILE_TEST':

  'PTP_1588_CLOCK_PCH' in drivers/ptp/Kconfig, which need depend on 'HAS_IOMEM'.


Signed-off-by: Chen Gang <gang.chen@...anux.com>
---
 include/asm-generic/io.h |   22 ++++++++++++++++++----
 1 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index d5afe96..301ce80 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -303,13 +303,18 @@ static inline void *phys_to_virt(unsigned long address)
 /*
  * Change "struct page" to physical address.
  *
- * This implementation is for the no-MMU case only... if you have an MMU
- * you'll need to provide your own definitions.
+ * This for the no-MMU, or no-IOMEM but still try to COMPILE_TEST cases.
+ * if you have an MMU and IOMEM, you'll need to provide your own definitions.
  */
-#ifndef CONFIG_MMU
+#if !defined(CONFIG_MMU) || \
+	(!defined(CONFIG_HAS_IOMEM) && defined(CONFIG_COMPILE_TEST))
 static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size)
 {
+#if !defined(CONFIG_MMU)
 	return (void __iomem*) (unsigned long)offset;
+#else
+	return NULL;
+#endif
 }
 
 #define __ioremap(offset, size, flags)	ioremap(offset, size)
@@ -325,7 +330,7 @@ static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size)
 static inline void iounmap(void __iomem *addr)
 {
 }
-#endif /* CONFIG_MMU */
+#endif /* !CONFIG_MMU || (!CONFIG_HAS_IOMEM && CONFIG_COMPILE_TEST) */
 
 #ifdef CONFIG_HAS_IOPORT
 #ifndef CONFIG_GENERIC_IOMAP
@@ -341,6 +346,15 @@ static inline void ioport_unmap(void __iomem *p)
 extern void __iomem *ioport_map(unsigned long port, unsigned int nr);
 extern void ioport_unmap(void __iomem *p);
 #endif /* CONFIG_GENERIC_IOMAP */
+#elif defined(CONFIG_COMPILE_TEST) /* CONFIG_HAS_IOPORT */
+static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
+{
+	return NULL;
+}
+
+static inline void ioport_unmap(void __iomem *p)
+{
+}
 #endif /* CONFIG_HAS_IOPORT */
 
 #ifndef xlate_dev_kmem_ptr
-- 
1.7.7.6



--------------------------patch end------------------------------------


Thanks.
-- 
Chen Gang

-- 
Chen Gang
--
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