[U-Boot] [PATCH 1/3] malloc_simple: Allow malloc_simple to be used with non stack RAM

[Hans de Goede]

Hi,

On 18-08-15 03:59, Simon Glass wrote:
> Hi Hans,
>
> On 17 August 2015 at 10:08, Hans de Goede <hdegoede at redhat.com> wrote:
>> Before this patch malloc_simple would always allocate a chunk of RAM from
>> the stack. This commit adds a CONFIG_SYS_MALLOC_F_BASE define, which when
>> set directly specifies the memory address to use for the heap with
>> malloc_simple.
>>
>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>> Reviewed-by: Simon Glass <sjg at chromium.org>
>> ---
>>   arch/arm/lib/crt0.S | 2 +-
>>   common/board_f.c    | 4 ++++
>>   common/dlmalloc.c   | 4 ++++
>>   common/spl/spl.c    | 3 +++
>>   4 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm/lib/crt0.S b/arch/arm/lib/crt0.S
>> index afd4f10..5e6619f 100644
>> --- a/arch/arm/lib/crt0.S
>> +++ b/arch/arm/lib/crt0.S
>> @@ -96,7 +96,7 @@ clr_gd:
>>          strlo   r0, [r1]                /* clear 32-bit GD word */
>>          addlo   r1, r1, #4              /* move to next */
>>          blo     clr_gd
>> -#if defined(CONFIG_SYS_MALLOC_F_LEN)
>> +#if defined(CONFIG_SYS_MALLOC_F_LEN) && !defined(CONFIG_SYS_MALLOC_F_BASE)
>>          sub     sp, sp, #CONFIG_SYS_MALLOC_F_LEN
>>          str     sp, [r9, #GD_MALLOC_BASE]
>>   #endif
>> diff --git a/common/board_f.c b/common/board_f.c
>> index c959774..7f3b96f 100644
>> --- a/common/board_f.c
>> +++ b/common/board_f.c
>> @@ -1050,9 +1050,13 @@ ulong board_init_f_mem(ulong top)
>>          arch_setup_gd(gd_ptr);
>>
>>   #ifdef CONFIG_SYS_MALLOC_F_LEN
>> +#if defined(CONFIG_SYS_MALLOC_F_BASE)
>> +       gd->malloc_base = CONFIG_SYS_MALLOC_F_BASE;
>> +#else
>>          top -= CONFIG_SYS_MALLOC_F_LEN;
>>          gd->malloc_base = top;
>>   #endif
>> +#endif
>>
>>          return top;
>>   }
>> diff --git a/common/dlmalloc.c b/common/dlmalloc.c
>> index b5bb051..9b14033 100644
>> --- a/common/dlmalloc.c
>> +++ b/common/dlmalloc.c
>> @@ -3264,7 +3264,11 @@ int mALLOPt(param_number, value) int param_number; int value;
>>   int initf_malloc(void)
>>   {
>>   #ifdef CONFIG_SYS_MALLOC_F_LEN
>> +#if defined(CONFIG_SYS_MALLOC_F_BASE)
>> +       gd->malloc_base = CONFIG_SYS_MALLOC_F_BASE;
>> +#else
>>          assert(gd->malloc_base);        /* Set up by crt0.S */
>> +#endif
>>          gd->malloc_limit = CONFIG_SYS_MALLOC_F_LEN;
>>          gd->malloc_ptr = 0;
>>   #endif
>> diff --git a/common/spl/spl.c b/common/spl/spl.c
>> index 94b01da..811452b 100644
>> --- a/common/spl/spl.c
>> +++ b/common/spl/spl.c
>> @@ -156,6 +156,9 @@ int spl_init(void)
>>   #if defined(CONFIG_SYS_MALLOC_F_LEN)
>>          gd->malloc_limit = CONFIG_SYS_MALLOC_F_LEN;
>>          gd->malloc_ptr = 0;
>> +#if defined(CONFIG_SYS_MALLOC_F_BASE)
>> +       gd->malloc_base = CONFIG_SYS_MALLOC_F_BASE;
>> +#endif
>>   #endif
>>          if (IS_ENABLED(CONFIG_OF_CONTROL) &&
>>                          !IS_ENABLED(CONFIG_SPL_DISABLE_OF_CONTROL)) {
>> --
>> 2.4.3
>>
>
> Why does this save memory?

See patch 2/3, which does #define CONFIG_SYS_MALLOC_SIMPLE when building
the SPL, removing common/dlmalloc.c and only using common/malloc_simple.c
both pre and post reloc.

We need this patch to do this because we do not have room on the stack
(which sits in SRAM) and setting CONFIG_SYS_MALLOC_F_LEN normally puts
the malloc_simple heap there.

We do however have room in DRAM and the SPL (which does not use device-
model on sunxi) does not need malloc until after DRAM has been brought
up, so we use this to point the malloc_simple.c heap at DRAM (far far
away from where u-boot.bin will be loaded).

> In general we should move away from hard-coding specific addresses I
> think, and just work out the memory from a single address, subtracting
> space for each area we need.

I understand and agree, but I've been unable to find another easy
solution for this, and now that we are adding nand support we are really
running out of space in the SPL on sunxi, and could really use the circa
3k (out of 24k total) dlmalloc is costing us.

Regards,

Hans