[ARM_LINUX] ioremap() allowing to map system memory...

[Prabhu nath]

In principle, ioremap() will return 0x00000000 if the physical address
passed is of memory.
I just want you to double check the address you have passed to ioremap().
In my experiment on x86 Desktop machine with 2GB RAM. I passed a physical
address 0x63ACD000. As expected it returned 0x00000000. I am running linux
version 3.5.1.


Regards,
Prabhunath G
Linux Trainer
Bangalore


On Fri, Mar 1, 2013 at 5:57 PM, sandeep kumar <coolsandyforyou at gmail.com>wrote:

> >Looks like you are trying to pass the address of physical memory to this
> function as a parameter and it is screwing up.
> Yes, i intentionally gave some physical address which is part of system
> memory.
> My problem infact is, it is not screwing up. It is allowing me to do that.
> Its not 'panic'ing
>
>
> On Fri, Mar 1, 2013 at 4:58 PM, Prabhu nath <gprabhunath at gmail.com> wrote:
>
>>
>>
>> On Fri, Mar 1, 2013 at 4:48 PM, sandeep kumar <coolsandyforyou at gmail.com>wrote:
>>
>>> Hi All
>>> I am using ARM based board.
>>> In mine,
>>> i did the following...
>>>
>>>  void __iomem *tcpm_base = ioremap_nocache(0x03B00000, 10*SZ_3MB);
>>>
>>> Actually i didnt reserve the 30MB memory @ 0x3B00000. But still the call
>>> is succesful and i am able to read the memory.
>>>
>>> In the logs it is just showing a warning, to fix my driver as i am
>>> calling ioremap() on system memory.
>>>
>>> However if i try to write something on that memory, then  only it is
>>> calling panic()..
>>>
>>> Don't you think it should throw panic()while calling the ioremap()
>>> itself. Because this sounds like a serious violation...
>>>
>>> What say?
>>>
>>
>> To my knowledge, ioremap is used only to map the device related physical
>> address to kernel virtual address. i.e. this function will only map either
>> device registers or device memory to kernel virtual address.
>>
>> Looks like you are trying to pass the address of physical memory to this
>> function as a parameter and it is screwing up.
>>
>> Please verify.
>>
>> Regards,
>> Prabhu
>>
>>  --
>>> With regards,
>>> Sandeep Kumar Anantapalli,
>>>
>>> _______________________________________________
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>
>>>
>>
>
>
> --
> With regards,
> Sandeep Kumar Anantapalli,
>
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