Re: [PATCH] include/asm-generic/io.h: add 'UML' case just like 'no-MMU'

[Chen Gang]

On 06/26/2013 02:54 PM, Richard Weinberger wrote:
> Hi!
> 
> Am 26.06.2013 08:31, schrieb Chen Gang:
>> For "User Mode Linux", it may enable 'MMU', but not need implement
>> ioremap and iounmap, so "include/asm-generic/io.h" need notice this
>> case to keep itself 'generic'.
>>
>> The related error (with allmodconfig, without pcap):
>>
>>     CC [M]  drivers/ptp/ptp_pch.o
>>   drivers/ptp/ptp_pch.c: In function ïpch_removeï:
>>   drivers/ptp/ptp_pch.c:571:3: error: implicit declaration of function ïiounmapï [-Werror=implicit-function-declaration]
>>   drivers/ptp/ptp_pch.c: In function ïpch_probeï:
>>   drivers/ptp/ptp_pch.c:621:2: error: implicit declaration of function ïioremapï [-Werror=implicit-function-declaration]
>>   drivers/ptp/ptp_pch.c:621:13: warning: assignment makes pointer from integer without a cast [enabled by default]
>>   cc1: some warnings being treated as errors
>>
>>
>> Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx>
>> ---
>>  arch/um/include/asm/Kbuild |    1 +
>>  include/asm-generic/io.h   |    6 +++---
>>  2 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
>> index b30f34a..a34ea5d 100644
>> --- a/arch/um/include/asm/Kbuild
>> +++ b/arch/um/include/asm/Kbuild
>> @@ -3,3 +3,4 @@ generic-y += hw_irq.h irq_regs.h kdebug.h percpu.h sections.h topology.h xor.h
>>  generic-y += ftrace.h pci.h io.h param.h delay.h mutex.h current.h exec.h
>>  generic-y += switch_to.h clkdev.h
>>  generic-y += trace_clock.h
>> +generic-y += io.h
> 
> We include that file already. See three lines above.
> 

Oh, really it is, thanks.

>> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
>> index d5afe96..e80331d 100644
>> --- a/include/asm-generic/io.h
>> +++ b/include/asm-generic/io.h
>> @@ -303,10 +303,10 @@ 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
>> + * This implementation is for the no-MMU or UML case only... if you have an MMU
>>   * you'll need to provide your own definitions.
>>   */
>> -#ifndef CONFIG_MMU
>> +#if !CONFIG_MMU || CONFIG_UML
>>  static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size)
>>  {
>>  	return (void __iomem*) (unsigned long)offset;
>> @@ -325,7 +325,7 @@ 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_UML */
>>  
>>  #ifdef CONFIG_HAS_IOPORT
>>  #ifndef CONFIG_GENERIC_IOMAP
>>
> 
> UML has no io memory but a MMU, so I'd argue that you better fix drivers/ptp/ptp_pch.c dependencies.
> _If_ ptp_pch.c really works without real io memory, you can look what I did in my GENERIC_IO series[1]
> to make nandsim work on UML. Maybe this helps.
> 

But "no io memory" is not the excuse to not define the related dummy
function.

The drivers internal code has already check the related return value,
so it is the architecture's duty to 'tell' the driver whether support
io memory (e.g. define ioremap, but return NULL).

So all together, I recommend the fix like below

--------------------------diff begin------------------------------------

diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index b30f34a..b282042 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -1,5 +1,5 @@
 generic-y += bug.h cputime.h device.h emergency-restart.h futex.h hardirq.h
 generic-y += hw_irq.h irq_regs.h kdebug.h percpu.h sections.h topology.h xor.h
-generic-y += ftrace.h pci.h io.h param.h delay.h mutex.h current.h exec.h
+generic-y += ftrace.h pci.h param.h delay.h mutex.h current.h exec.h
 generic-y += switch_to.h clkdev.h
 generic-y += trace_clock.h
diff --git a/arch/um/include/asm/io.h b/arch/um/include/asm/io.h
new file mode 100644
index 0000000..00f3cd8
--- /dev/null
+++ b/arch/um/include/asm/io.h
@@ -0,0 +1,21 @@
+#ifndef UML_IO_H
+#define UML_IO_H
+
+#include <asm-generic/io.h>
+
+/*
+ * UML does not support io memory, so return NULL.
+ */
+static inline void __iomem *ioremap(phys_addr_t offset, unsigned long size)
+{
+	return NULL;
+}
+
+#define ioremap_nocache ioremap
+#define ioremap_wc ioremap_nocache
+
+static inline void iounmap(void __iomem *addr)
+{
+}
+
+#endif /* UML_IO_H */

--------------------------diff end------------------------------------


Thanks.
-- 
Chen Gang

Asianux Corporation
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/