Files
rtems/bsps/sh/shsim
Sebastian Huber 511dc4b2be Rework initialization and interrupt stack support
Statically initialize the interrupt stack area
(_Configuration_Interrupt_stack_area_begin,
_Configuration_Interrupt_stack_area_end, and
_Configuration_Interrupt_stack_size) via <rtems/confdefs.h>.  Place the
interrupt stack area in a special section ".rtemsstack.interrupt".  Let
BSPs define the optimal placement of this section in their linker
command files (e.g. in a fast on-chip memory).

This change makes makes the CPU_HAS_SOFTWARE_INTERRUPT_STACK and
CPU_HAS_HARDWARE_INTERRUPT_STACK CPU port defines superfluous, since the
low level initialization code has all information available via global
symbols.

This change makes the CPU_ALLOCATE_INTERRUPT_STACK CPU port define
superfluous, since the interrupt stacks are allocated by confdefs.h for
all architectures.  There is no need for BSP-specific linker command
file magic (except the section placement), see previous ARM linker
command file as a bad example.

Remove _CPU_Install_interrupt_stack().  Initialize the hardware
interrupt stack in _CPU_Initialize() if necessary (e.g.
m68k_install_interrupt_stack()).

The optional _CPU_Interrupt_stack_setup() is still useful to customize
the registration of the interrupt stack area in the per-CPU information.

The initialization stack can reuse the interrupt stack, since

  * interrupts are disabled during the sequential system initialization,
    and

  * the boot_card() function does not return.

This stack resuse saves memory.

Changes per architecture:

arm:

  * Mostly replace the linker symbol based configuration of stacks with
    the standard <rtems/confdefs.h> configuration via
    CONFIGURE_INTERRUPT_STACK_SIZE.  The size of the FIQ, ABT and UND
    mode stack is still defined via linker symbols.  These modes are
    rarely used in applications and the default values provided by the
    BSP should be sufficient in most cases.

  * Remove the bsp_processor_count linker symbol hack used for the SMP
    support. This is possible since the interrupt stack area is now
    allocated by the linker and not allocated from the heap.  This makes
    some configure.ac stuff obsolete.  Remove the now superfluous BSP
    variants altcycv_devkit_smp and realview_pbx_a9_qemu_smp.

bfin:

  * Remove unused magic linker command file allocation of initialization
    stack.  Maybe a previous linker command file copy and paste problem?
    In the start.S the initialization stack is set to a hard coded value.

lm32, m32c, mips, nios2, riscv, sh, v850:

  * Remove magic linker command file allocation of initialization stack.
    Reuse interrupt stack for initialization stack.

m68k:

  * Remove magic linker command file allocation of initialization stack.
    Reuse interrupt stack for initialization stack.

powerpc:

  * Remove magic linker command file allocation of initialization stack.
    Reuse interrupt stack for initialization stack.

  * Used dedicated memory region (REGION_RTEMSSTACK) for the interrupt
    stack on BSPs using the shared linkcmds.base (replacement for
    REGION_RWEXTRA).

sparc:

  * Remove the hard coded initialization stack.  Use the interrupt stack
    for the initialization stack on the boot processor.  This saves
    16KiB of RAM.

Update #3459.
2018-06-27 08:58:16 +02:00
..

Simple BSP for the SH simulator built into gdb.

Simulator Invocation
====================
sh-rtems[elf|]-gdb <executable>
(gdb) target sim
(gdb) set archi [sh|sh2]
(gdb) load <executable>
(gdb) run

Status
======

* The simulator invocation procedure outlined above produces error messages
with gdb-5.0, nevertheless seems to work. With gdb versions > 5.0 these
error messages are gone. I.e. if you plan to seriously work with the gdb
simulator better use gdb versions > 5.0.

* gdb's simulator is not able to correctly emulate memory areas esp. shadowing
and non-consecutive memory. I.e. access to memory areas besides area 0 will 
(bogusly) generate SIGBUS exceptions.  This includes access to area 5 
(On-chip peripherials) and prevents simulation of configuration and access
to on-chip peripherials.

* Due to limitations of the simulator you will only be able to run
applications which do not try to access any SH control registers.

Currently, this excludes all applications, which apply timers and serial 
devices, i.e. almost any real world application.

* This BSP supports 3 different console devices (cf. configure --help):
- trap34, an interface base on gdb's trap34 emulation. Known to work with
  gdb-5.0.
- gdbsci1, a stripped down sci device driver adapted to apply gdb's sci1
emulation. This is known to fail with gdb-5.0, because of a bug in gdb-5.0's 
sh-sim, a patch is submitted, but .. ~==
- devnull, redirection of console io to /dev/null. Try to single step this,
if you want to understand the details on how SH-RTEMS console redirection
works.

NOTE: the trap34 interface is incomplete and is temporarily disabled
inside of configure.in.