* [U-Boot] Memset 0 in heap initialization?
@ 2010-12-09 16:14 Dirk Behme
2011-01-18 5:17 ` Dirk Behme
0 siblings, 1 reply; 3+ messages in thread
From: Dirk Behme @ 2010-12-09 16:14 UTC (permalink / raw)
To: u-boot
In common/dlmalloc.c in the heap initialization mem_malloc_init() [1]
it looks like the whole heap is initialized with zero:
memset((void *)mem_malloc_start, 0, size);
What's the reason for doing this? I know that the .bss segment has to
be zeroed at system start up, but why doing this for the heap, too? It
was my understanding that one could make no assumption about the
initial content of memory returned by malloc() (?).
Sorry if I miss the obvious ;)
Thanks
Dirk
[1]
http://git.denx.de/?p=u-boot.git;a=blob;f=common/dlmalloc.c;h=e9bab09b8eac7c0ec4900a3685f15a807b448c31;hb=refs/heads/master#l1529
^ permalink raw reply [flat|nested] 3+ messages in thread
* [U-Boot] Memset 0 in heap initialization?
2010-12-09 16:14 [U-Boot] Memset 0 in heap initialization? Dirk Behme
@ 2011-01-18 5:17 ` Dirk Behme
2011-01-18 5:55 ` Kumar Gala
0 siblings, 1 reply; 3+ messages in thread
From: Dirk Behme @ 2011-01-18 5:17 UTC (permalink / raw)
To: u-boot
On 09.12.2010 17:14, Dirk Behme wrote:
>
> In common/dlmalloc.c in the heap initialization mem_malloc_init() [1]
> it looks like the whole heap is initialized with zero:
>
> memset((void *)mem_malloc_start, 0, size);
>
> What's the reason for doing this? I know that the .bss segment has to
> be zeroed at system start up, but why doing this for the heap, too? It
> was my understanding that one could make no assumption about the
> initial content of memory returned by malloc() (?).
>
> Sorry if I miss the obvious ;)
>
> Thanks
>
> Dirk
>
> [1]
> http://git.denx.de/?p=u-boot.git;a=blob;f=common/dlmalloc.c;h=e9bab09b8eac7c0ec4900a3685f15a807b448c31;hb=refs/heads/master#l1529
Any idea regarding this?
Thanks
Dirk
^ permalink raw reply [flat|nested] 3+ messages in thread
* [U-Boot] Memset 0 in heap initialization?
2011-01-18 5:17 ` Dirk Behme
@ 2011-01-18 5:55 ` Kumar Gala
0 siblings, 0 replies; 3+ messages in thread
From: Kumar Gala @ 2011-01-18 5:55 UTC (permalink / raw)
To: u-boot
On Jan 17, 2011, at 11:17 PM, Dirk Behme wrote:
> On 09.12.2010 17:14, Dirk Behme wrote:
>>
>> In common/dlmalloc.c in the heap initialization mem_malloc_init() [1]
>> it looks like the whole heap is initialized with zero:
>>
>> memset((void *)mem_malloc_start, 0, size);
>>
>> What's the reason for doing this? I know that the .bss segment has to
>> be zeroed at system start up, but why doing this for the heap, too? It
>> was my understanding that one could make no assumption about the
>> initial content of memory returned by malloc() (?).
>>
>> Sorry if I miss the obvious ;)
>>
>> Thanks
>>
>> Dirk
>>
>> [1]
>> http://git.denx.de/?p=u-boot.git;a=blob;f=common/dlmalloc.c;h=e9bab09b8eac7c0ec4900a3685f15a807b448c31;hb=refs/heads/master#l1529
>
> Any idea regarding this?
Part of this is because we define MORECORE_CLEARS 1 which does assume memory is zero'd out.
- k
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2010-12-09 16:14 [U-Boot] Memset 0 in heap initialization? Dirk Behme
2011-01-18 5:17 ` Dirk Behme
2011-01-18 5:55 ` Kumar Gala
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