[U-Boot] [U-Boot, v3, 1/2] fs: fat: dynamically allocate memory for temporary buffer

[Alexander Graf]

On 21.02.19 09:41, Marek Vasut wrote:
> On 2/21/19 9:40 AM, Chee, Tien Fong wrote:
>> On Thu, 2019-02-21 at 09:29 +0100, Alexander Graf wrote:
>>>
>>> On 21.02.19 09:23, Chee, Tien Fong wrote:
>>>>
>>>> On Thu, 2019-02-21 at 08:45 +0100, Michal Simek wrote:
>>>>>
>>>>> Hi Tom,
>>>>>
>>>>> On 20. 02. 19 2:58, Tom Rini wrote:
>>>>>>
>>>>>>
>>>>>> On Mon, Feb 11, 2019 at 02:56:19PM +0800, tien.fong.chee at intel.
>>>>>> com
>>>>>> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> From: Tien Fong Chee <tien.fong.chee at intel.com>
>>>>>>>
>>>>>>> Drop the statically allocated get_contents_vfatname_block and
>>>>>>> dynamically allocate a buffer only if required. This saves
>>>>>>> 64KiB of memory.
>>>>>>>
>>>>>>> Signed-off-by: Stefan Agner <stefan.ag... at toradex.com>
>>>>>>> Signed-off-by: Tien Fong Chee <tien.fong.chee at intel.com>
>>>>>> Applied to u-boot/master, thanks!
>>>>> please remove this patch (better both of them because they were
>>>>> in
>>>>> series)
>>>> I think patch 2/2 should be safe, because no memory size is
>>>> changed.
>>>> Basically, it just to release the allocated memory immediately when
>>>> it's not required, so other can re-use it.
>>>>
>>>>>
>>>>> because they are breaking at least ZynqMP SPL. It is also too
>>>>> late in cycle to create random fix.
>>>>>
>>>>> You can't simply move 64KB from code to malloc without reflecting
>>>>> this
>>>>> by changing MALLOC space size.
>>>>>
>>>>> Other boards with SPL fat could be also affected by this if they
>>>>> don't
>>>>> allocate big malloc space.
>>>> So, any suggestion to get the patch 1/2 accepted? inform all board
>>>> maintainers to test it out?
>>> You already received feedback that it does break ZynqMP, so the
>>> current
>>> approach won't work.
>>>
>>> How about you create a new kconfig option that allows you to say
>>> whether
>>> you want to use malloc or .bss for temporary data in the FAT driver.
>>> You
>>> can then have an _SPL_ version of that kconfig and check for it with
>>> IS_ENABLED() which should automatically tell you the right answer
>>> depending on whether you're in an SPL build or not.
>>>
>>> Then you can set the SPL version to default malloc and the non-SPL
>>> version to default .bss.
>> Marek and Tom rini,
>>
>> Are you guys okay with Alex's suggestion?
> 
> I'm not a big fan of adding more and more ifdeffery.
> Is there some other option ?

Is RAM up already at this point? Maybe we could improve the SPL malloc
mechanism to move allocations into DRAM once it's available.


Alex