Re: [lwip-users] MEM_SIZE

[Giuseppe Modugno]

Il 15/03/2018 11:28, Simon Goldschmidt ha scritto:

Giuseppe Modugno wrote:

[..]
I think with the following options:

#define MEM_LIBC_MALLOC  0
#define MEM_USE_POOLS  1
#define MEM_USE_CUSTOM_POOLS 1  /* Needed by MEM_USE_POOLS */

It's MEMP_USE_CUSTOM_POOLS, not MEM_USE_CUSTOM_POOLS.


It was a typo.


And it compiles for me, see the win32 port for an example.


Yes, now it compiles without errors. The file lwippools.h lacked the 
LWIP_MALLOC_MEMPOOL macros to define the set of pools used by lwip in 
case MEM_USE_POOLS is set.



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Re: [lwip-users] MEM_SIZE

[Simon Goldschmidt]

Giuseppe Modugno wrote:
> [..]
> I think with the following options:
> 
> #define MEM_LIBC_MALLOC  0
> #define MEM_USE_POOLS  1
> #define MEM_USE_CUSTOM_POOLS 1  /* Needed by MEM_USE_POOLS */

It's MEMP_USE_CUSTOM_POOLS, not MEM_USE_CUSTOM_POOLS. And it compiles for me,
see the win32 port for an example.

Simon

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Re: [lwip-users] MEM_SIZE

[Simon Goldschmidt]

Giuseppe Modugno wrote:
> [..]
> In my case, I have a completely free (not used by the linker) 32kB RAM 
> region starting from 0x2007C000. To instruct lwip to use that region for 
> heap, I think I have to define:
> 
> #define MEM_SIZE  (32 * 1024 - 1 * SIZEOF_STRUCT_MEM)
> #define LWIP_RAM_HEAP_POINTER ( (void *)0x2007C000 )
> 
> Supposing we don't need other additional space for alignment.
> In this case the total free heap memory available for data is exactly 
> MEM_SIZE, that is less than 32kB.
> 
> Is it correct?

I think so, yes. However, your definition of MEM_SIZE won't compile outside
of mem.c. Maybe it would be better to rework the code to use MEM_SIZE as
size of the available block, at least if an external block is used...

Simon

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Re: [lwip-users] Problems when setting MEMP_MEM_MALLOC

[Giuseppe Modugno]

Il 14/03/2018 21:24, Nathan Hartman ha scritto:

On Mar 14, 2018, at 3:24 PM, "goldsi...@gmx.de"  wrote:

On 14.03.2018 17:09, Giuseppe Modugno wrote:
#define MEM_LIBC_MALLOC   1

If I try to set MEMP_MEM_MALLOC, I have some strange problems.

I suspect threading issues. I checked on win32 and it seems to work fine. In 
the end, there's not really much lwIP does here, everything is delegated to 
your C library's malloc code. Maybe that code isn't thread-safe? In that case, 
you need to define mem_clib_*() to wrapper functions that protect the heap.

Just a guess: it sounds like your linker script may be placing the heap in the 
wrong place, not allocating one at all, and/or it may not be where your C 
library expects it to be.

It is very important to give your application enough stack and enough heap, and 
to make sure they do not clobber each other as they grow.


I'm starting thinking about an issue similar to "out of memory". Every 
time the custom file is opened, a mem_malloc(1024) is called and every 
time the pointer returned is increased. I'm sure the allocated space is 
freed in fs_close_custom. Maybe it's a problem with fragmentation... I 
have to make additional tests.



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Re: [lwip-users] Problems when setting MEMP_MEM_MALLOC

[Giuseppe Modugno]

Il 14/03/2018 20:24, goldsi...@gmx.de ha scritto:

On 14.03.2018 17:09, Giuseppe Modugno wrote:

#define MEM_LIBC_MALLOC   1

If I try to set MEMP_MEM_MALLOC, I have some strange problems.


I suspect threading issues. I checked on win32 and it seems to work 
fine. In the end, there's not really much lwIP does here, everything 
is delegated to your C library's malloc code. Maybe that code isn't 
thread-safe? In that case, you need to define mem_clib_*() to wrapper 
functions that protect the heap.


I'm using NewlibNano as C library. However I'm using NOSYS=1 and I don't 
use threads. In my application, "threads" are only interrupt service 
routines, but I don't call mem_malloc from any ISR (I don't think lwip 
uses interrupts at all).


So I don't think it is caused by a threading issue.


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Re: [lwip-users] MEM_SIZE

[Giuseppe Modugno]

Il 14/03/2018 16:42, Giuseppe Modugno ha scritto:

I was experimenting with lwip memory allocator. I defined:

#define MEM_LIBC_MALLOC  0
#define MEM_USE_POOLS  0
#define MEM_SIZE  (32 * 1024)
#define LWIP_RAM_HEAP_POINTER  ( (void *)0x2007C000 )

I'm using LPC1768 that has a 32kB SRAM block starting from address 
0x2007C000. However I have a Hard Fault error during mem_init(), 
because ram_end is initialized to 0x2007C000 + (32*1024), that is over 
the available memory.


So MEM_SIZE should be smaller than available heap memory.


Another question regarding memory management of lwip.

I understood lwip uses memory pools for many things (TCP pcbs, UDP pcbs, 
RAW pcb, timers and so on). The memory pools are defined in 
include/lwip/priv/memp_std.h.
They aren't allocated from the heap, but from pools. I think because it 
is supposed they must be allocated frequently, so they could bring to 
fragmentation and the allocation should be fast.


Does lwip use strictly heap (mem_malloc) for its own purposes? It seems 
yes (I see some mem_malloc calls in httpd, dhcp, pbuf, ...).

Is it possible to compile lwip so it doesn't use heap at all?

I think with the following options:

#define MEM_LIBC_MALLOC  0
#define MEM_USE_POOLS  1
#define MEM_USE_CUSTOM_POOLS 1  /* Needed by MEM_USE_POOLS */

In this way, heap implementation isn't a real heap, but a set of 
different-sized pools. This set is defined in arhc/lwippools.h. Is it 
correct?


I tried to compile with this options, but I have this error (for example 
compiling memp.c):


mingw32-gcc.exe -Wall -std=c11 -Wall -pedantic -Wparentheses 
-Wsequence-point -Wextra -Wundef -Wshadow -Wpointer-arith -Wcast-qual 
-Wwrite-strings -Wold-style-definition -Wcast-align -Wmissing-prototypes 
-Wredundant-decls -Wnested-externs -Wno-address -Wunreachable-code 
-Wuninitialized -Wlogical-op -Wno-format -g -DLWIP_DEBUG -DDEBUG 
-Isrc\lwip\src\include -Isrc -Isrc\ports\mingw\lwip_arch 
-Isrc\ports\mingw -Isrc\bus -Isrc\WpdPack\Include -I..\..\..\work_git 
-Isrc\lwip\src\include\lwip\apps -c 
C:\Users\Giuseppe\Documents\work_git\webserver\webserver\src\lwip\src\core\memp.c 
-o mingw\Debug\src\lwip\src\core\memp.o

In file included from src\lwip\src\include/lwip/memp.h:58:0,
 from 
C:\Users\Giuseppe\Documents\work_git\webserver\webserver\src\lwip\src\core\memp.c:48:
src\lwip\src\include/lwip/priv/memp_priv.h:89:5: error: expected 
expression before ')' token

 ) ,
 ^


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Re: [lwip-users] MEM_SIZE

[Giuseppe Modugno]

Il 14/03/2018 20:26, goldsi...@gmx.de ha scritto:

On 14.03.2018 16:42, Giuseppe Modugno wrote:

I was experimenting with lwip memory allocator. I defined:

#define MEM_LIBC_MALLOC  0
#define MEM_USE_POOLS  0
#define MEM_SIZE  (32 * 1024)
#define LWIP_RAM_HEAP_POINTER  ( (void *)0x2007C000 )

I'm using LPC1768 that has a 32kB SRAM block starting from address
0x2007C000. However I have a Hard Fault error during mem_init(), because
ram_end is initialized to 0x2007C000 + (32*1024), that is over the
available memory.

So MEM_SIZE should be smaller than available heap memory.


Is that a question? Or an action request? 

It was a question, even if I forgot to add a question mark :-)

To my understanding, the comment above #ifndef LWIP_RAM_HEAP_POINTER 
in mem.c clearly states that enough memory is required. It does NOT 
say that amount is MEM_SIZE. If you want, create a patch with a better 
documentation and we could apply it.
Ah ok, I now understand the comment "we need one struct mem at the end 
and some room for alignment".


MEM_SIZE isn't the total available memory for heap management (including 
accessory structs), but it is the *useful* memory space the application 
needs for the heap (excluding accessory structs). For example, if 
MEM_SIZE is 1024, I can be sure one malloc(1024) won't fail.


In my case, I have a completely free (not used by the linker) 32kB RAM 
region starting from 0x2007C000. To instruct lwip to use that region for 
heap, I think I have to define:


#define MEM_SIZE  (32 * 1024 - 1 * SIZEOF_STRUCT_MEM)
#define LWIP_RAM_HEAP_POINTER ( (void *)0x2007C000 )

Supposing we don't need other additional space for alignment.
In this case the total free heap memory available for data is exactly 
MEM_SIZE, that is less than 32kB.


Is it correct?

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