[U-Boot] [PATCH] malloc_simple: Add simple malloc free function

[Chin Liang See]

On Thu, 2016-08-04 at 07:30 +0200, Marek Vasut wrote:
> On 08/03/2016 05:22 PM, Chin Liang See wrote:
> 
> Hi,

Hi Marek,

> 
> [...]
> > > > It's the fat driver which is utilizing the malloc.
> > > 
> > > So fat is allocating stuff without freeing it ? I wonder if we
> > > should
> > > either fix fat or use full malloc in SPL on A10 . I am not really
> > > fond
> > > of adding more stuff into simple malloc (to keep it small and 
> > > simple).
> > 
> > Actually fat driver is good where it invoke malloc and free during
> > the
> > operation. Just that with existing malloc, there is no free
> > implementation and memory keep "push" every time malloc invoked.
> 
> And I agree with Simon that we should look into the FAT driver and
> fix
> it. Is that not possible ?


Definitely as seems everyone believe this should be the right way to
go.

> 
> > > > > Your design breaks in the scenario where someone does big
> > > > > malloc
> > > > > followed by two small mallocs if I understand it correctly.
> > > > > This
> > > > > doesn't scale and is a hack.
> > > > > 
> > > > 
> > > > Actually the proposed free is a simple implementation which
> > > > acts as
> > > > stack push and pop with depth of 2. This is to enhance existing
> > > > implementation which don't handle the pop. This get worst
> > > > especially
> > > > dealing with fat driver.
> > > 
> > > Well, how does it handle my example? It doesn't and it fails to
> > > help
> > > in
> > > such case, right ?
> > 
> > I was thinking what is the correct depth while trying to keep
> > things
> > simple. From the FAT access testing with SD and eMMC, depth of 2
> > works
> > well by cutting lot of memory consumption by simple malloc
> > implementation. Any thoughts whether should have more flexibility?
> 
> You still didn't answer my question -- how will this handle my
> example
> usecase ?
> 

I did and wonder my email server having issue again. For this case,
yah, it will not being handle as we try to keep it simple by having
depth of 2. FYI, the 2 is being derived from my experiment of FAT
driver access with SD and eMMC devices. We can enhance that but
probably that might not a good idea per Simon suggested.

Thanks
Chin Liang