Re: g++, strange behavior issues

Also there's macros in Linux that return/test for errors via setting
pointers to values < 4096.  Because "these addresses are NEVER valid".
;) Not sure how uCLinux deals with this, other than people avoiding
putting valid memory address near 0.

Just another challenge with micros.

On Thu, Feb 13, 2014 at 12:37 AM, Angelo Dureghello <[email protected]> wrote:
> That was exactly my case, a null pointer, and ram starts from 0x0 in the map
> :).
> I will keep in mind this thing for the future.
>
> Still thanks.
>
> Regards
> Angelo
>
>
> On 13/02/2014 03:29, Gavin Lambert wrote:
>>
>> Quoth Larry Baker:
>>>
>>> Yes, this is indeed what can happen on a system like uClinux that does
>>> not have an MMU (memory management unit).  The tiny controller chips
>>> that uClinux targets do not protect any part of the memory from being
>>> accidentally corrupted.  As long as the memory being accessed exists,
>>> there is no hardware fence between a user program and the rest of memory.
>>
>> It's especially fun when address 0 is valid memory (which is not
>> uncommon).
>> Then you don't get crashes from null pointer accesses, which most
>> developers
>> expect (and some can be lazy about protecting against, thinking that
>> they'll
>> find it during debugging).
>>
>> I always try to configure the target device's memory map such that
>> addresses
>> near 0 remain invalid, whenever possible -- but some targets don't support
>> that.
>>
>>
>
> _______________________________________________
> uClinux-dev mailing list
> [email protected]
> http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
> This message was resent by [email protected]
> To unsubscribe see:
> http://mailman.uclinux.org/mailman/options/uclinux-dev
_______________________________________________
uClinux-dev mailing list
[email protected]
http://mailman.uclinux.org/mailman/listinfo/uclinux-dev
This message was resent by [email protected]
To unsubscribe see:
http://mailman.uclinux.org/mailman/options/uclinux-dev