[ECOS] Context switching fails under LPC22xx/LPC21xx

[Sergei Gavrikov]

On Thu, Feb 21, 2008 at 10:17:07AM -0800, Sivan Toledo wrote:
> 
> Hi,
> 
> We successfully built an eCos library (hal and default templates) and
> HAL programs for an LPC2214 board and for an LPC2119 board. I used
> Sergei Gavrilov's code and both work fine when used in HAL-only mode
> without a scheduler.
> 
> When we try to run twothreads.c, the program runs cyg_user_start but
> then resets the processor, which causes cyg_user_start to run again,
> and on on indefinitely.
> 
> We believe that the problem is that the stack frame is not aligned on
> a 32-bit boundary. This seems to throw an exception that causes the
> HAL to reset. We tried to allocate the stack buffers in different ways
> to fix that, but it does not seem to help.
> 
> Any idea what might be causing this and how to fix it?
> 
> Thanks, Sivan Toledo and Aviad Zuc.

Hello:

I won't stop on LPC2214. The CPU has an external bus and I hope that you
have enough external RAM to build RAM image and to resolve a problem
using GDB and an eCos tracing.

The LPC2119 hasn't external bus, so you try to manage the example using
16K on-chip RAM only, don't you? The `twothreads.c` is a bloat example
which uses LIBC cats: main(), printf(). It seems for me that you did
modify some things to reduce twotheads's appetite...

Public CVS tree has mcb2100 target (board from Keil with LPC2119 CPU). I
tried to build the twothreads example for the target

chdir <some where>

ecosconfig new mcb2100
ecosconfig tree
make

SRCS=$ECOS_REPOSITORY/../examples/twothreads.c DST=twothreads \
$ECOS_REPOSITORY/../examples/build_Makefile .

make -f Makefile

So far, so good. I got twothreads.o for LPC2119.

make -f Makefile twothreads

arm-elf/bin/ld: address 0x40006e08 of twothreads section .bss is not within region ram

We have a deficit of RAM (> 8K) with the default settings. So, we have
to 1) revise the default ecos settings; 2) revise twothread.c source (no
printf(), no main()).

rm -r *
ecosconfig new mcb2100
ecosconfig remove CYGPKG_LIBC_STARTUP ;# free 8K
ecosconfig tree
make

# remove bloat printf() and reduce the default twothread's stack sizes
sed 's/printf/diag_printf/;s/4096/2048/' \
< $ECOS_REPOSITORY/../examples/twothreads.c > twothreads.c

# build Makefile
SRCS=twothreads.c DST=twothreads \
$ECOS_REPOSITORY/../examples/build_Makefile .

# rude tweak (no main())
echo "ACTUAL_CFLAGS += -Dmain=cyg_user_start" >> Make.params

make -f Makefile

arm-elf-size twothreads
   text    data     bss     dec     hex filename
  25268     828   11980   38076    94bc twothreads

It's seems for me this should work. If it won't. Compare your own
hal_platform_setup.h, mlt* stuff for LPC2129 with the MCB2100' one.

... if that still not working try to apply an attached patch and
_rebuild_ _all_ from scratch:

patch -p1 -d $ECOS_REPOSITORY < lpc2xxx_misc.c.patch

I hope the twothreads example will be run even on your LPC2119 board.

Sergei

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