[U-Boot] [PATCH v4 1/2] dlmalloc: fix malloc range at end of ram

[Heiko Schocher <hs@denx.de>]

Hello Simon,

Am 25.04.2019 um 21:24 schrieb Simon Goldschmidt:
> Am 25.04.2019 um 12:50 schrieb Tom Rini:
>> On Thu, Apr 25, 2019 at 09:32:22AM +0200, Simon Goldschmidt wrote:
>>> On Thu, Apr 25, 2019 at 1:59 AM Simon Glass <sjg@chromium.org> wrote:
>>>>
>>>> Hi,
>>>>
>>>> On Wed, 24 Apr 2019 at 05:53, Tom Rini <trini@konsulko.com> wrote:
>>>>>
>>>>> On Wed, Apr 24, 2019 at 01:49:52PM +0200, Simon Goldschmidt wrote:
>>>>>> On Wed, Apr 24, 2019 at 1:27 PM Tom Rini <trini@konsulko.com> wrote:
>>>>>>>
>>>>>>> On Tue, Apr 23, 2019 at 09:54:10PM -0600, Simon Glass wrote:
>>>>>>>> On Mon, 1 Apr 2019 at 14:01, Simon Goldschmidt
>>>>>>>> <simon.k.r.goldschmidt@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> If the malloc range passed to mem_malloc_init() is at the end of address
>>>>>>>>> range and 'start + size' overflows to 0, following allocations fail as
>>>>>>>>> mem_malloc_end is zero (which looks like uninitialized).
>>>>>>>>>
>>>>>>>>> Fix this by subtracting 1 of 'start + size' overflows to zero.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
>>>>>>>>> ---
>>>>>>>>>
>>>>>>>>> Changes in v4: None
>>>>>>>>> Changes in v3: None
>>>>>>>>>
>>>>>>>>>   common/dlmalloc.c | 4 ++++
>>>>>>>>>   1 file changed, 4 insertions(+)
>>>>>>>>
>>>>>>>> Reviewed-by: Simon Glass <sjg@chromium.org>
>>>>>>>
>>>>>>> So, the problem with this patch is that it increases the generic malloc
>>>>>>> code size ever so slightly and blows up smartweb :(
>>>>>>
>>>>>> Ehrm, ok, so how do we proceed?
>>>>>
>>>>> A good question.  Take a look at spl/u-boot-spl.map on smartweb and see
>>>>> if, of the malloc functions it doesn't discard there's something that
>>>>> maybe could be optimized somewhere?
>>>>
>>>> I wonder if we should have a Kconfig option like SPL_CHECKS which
>>>> enables these sorts of minor checks, which may only fix one board at
>>>> the cost of code size?
>>>>
>>>> Then it could be enabled by default, but disabled on this board?
>>>
>>> For a bigger change, this might be an idea, but for a change that I can cut
>>> down to 16 or even 8 bytes code size increasement, I don't think having a
>>> new option would be good.
>>>
>>> Anyway, I just tried at work and I don't get the overflow. Tom, which gcc
>>> are you using to get the size error? It works for me on Debian 9 but doesn't
>>> work with Ubuntu (both times, default cross compiler toolchain installed).
>>
>> I'm using the gcc-7.3 from kernel.org that we use in travis/etc.
> 
> Ok, so I have gcc-7.3 on my Ubuntu machine as well. I don't know why 6.3 seems to produce smaller 
> binaries (I thought they were getting smaller with new versions, not larger).
> 
> However, I've stripped down that patch to +8 Bytes only and sent v5.

Thanks!

Sorry for digging so late in, but I was on vacation...

Hmm.. the smartweb board has only 4k sram for SPL, and I have no chance
to convert it to DM to get rid of some compiler warnings ...

I am unsure what to do now with this hardware ...

bye,
Heiko
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