Is there a low-level Python API in Simics for setting breakpoints with prefixes? - Stack Overflow

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Simics 6 had a "set-prefix" front-end command that could be used following creation of a breakpoint, e.g.,

    for bp in self.breakpoint_list:
        bp.break_num = SIM_breakpoint(bp.object, bp.addr_type, bp.mode, bp.addr, bp.length, bp.flags)
        if bp.prefix is not None:
            command = 'set-prefix %d "%s"' % (bp.break_num, bp.prefix)
            SIM_run_alone(SIM_run_command, command)

The set-prefix command is deprecated out of Simics 7, and the documenation suggests using the bp.memory.break command instead. However, the bp.memory.break command uses the front end processor which is inefficent from within breakpoint-intensive scripts.

Using a mix of SIM_breakpoint (for efficiency) and bp.memory.break (to set a prefix) seems dangerous because the bp.manager and SIM_breakpoint are not exclusive on their use of breakpoint numbers. For example:

from simics import *
import cli
'''
  Demonstrate how SIM_breakpoint and bp.memory.break do not use exclusive breakpoint numbers
'''
def theHap(cpu, the_obj, the_break, memory):
    print('in theHap break %d memory 0x%x' % (the_break, memory.logical_address))

cmd = 'ubuntu.get-processor-list'
proclist = SIM_run_command(cmd)
cpu = SIM_get_object(proclist[0])

print('Our cpu is %s' % cpu.name)

bp1 = SIM_breakpoint(cpu.current_context, Sim_Break_Linear, Sim_Access_Execute, 0x00000000b774d753, 1, 0)
print('added break %s with SIM_breakpoint' % bp1)
proc_hap = SIM_hap_add_callback_index("Core_Breakpoint_Memop", theHap, cpu, bp1)
print('Hap set on breakpoint %d' % bp1)

bp2 = SIM_run_command('bp.memory.break 0x00000000b774d75d')
print('added break %s with bp.memory.break' % bp2)
proc_hap = SIM_hap_add_callback_index("Core_Breakpoint_Memop", theHap, cpu, bp2)
print('Hap set on breakpoint %d' % bp2)

Results in:

   simics> run-script prefix.py
   Our cpu is ubuntu.mb.cpu0.core[0][0]
   added break 1 with SIM_breakpoint
   Hap set on breakpoint 1
   added break 1 with bp.memory.break
   Hap set on breakpoint 1
   NIL
   simics> c
   in theHap break 1 memory 0xb774d753
   in theHap break 1 memory 0xb774d753
   [ubuntu.cell_context] Breakpoint 1: ubuntu.cell_context 'x' access to v:0xb774d75d len=3

Is there a low-level Simics Python API for setting breakpoints with prefixes?

Simics 6 had a "set-prefix" front-end command that could be used following creation of a breakpoint, e.g.,

    for bp in self.breakpoint_list:
        bp.break_num = SIM_breakpoint(bp.object, bp.addr_type, bp.mode, bp.addr, bp.length, bp.flags)
        if bp.prefix is not None:
            command = 'set-prefix %d "%s"' % (bp.break_num, bp.prefix)
            SIM_run_alone(SIM_run_command, command)

The set-prefix command is deprecated out of Simics 7, and the documenation suggests using the bp.memory.break command instead. However, the bp.memory.break command uses the front end processor which is inefficent from within breakpoint-intensive scripts.

Using a mix of SIM_breakpoint (for efficiency) and bp.memory.break (to set a prefix) seems dangerous because the bp.manager and SIM_breakpoint are not exclusive on their use of breakpoint numbers. For example:

from simics import *
import cli
'''
  Demonstrate how SIM_breakpoint and bp.memory.break do not use exclusive breakpoint numbers
'''
def theHap(cpu, the_obj, the_break, memory):
    print('in theHap break %d memory 0x%x' % (the_break, memory.logical_address))

cmd = 'ubuntu.get-processor-list'
proclist = SIM_run_command(cmd)
cpu = SIM_get_object(proclist[0])

print('Our cpu is %s' % cpu.name)

bp1 = SIM_breakpoint(cpu.current_context, Sim_Break_Linear, Sim_Access_Execute, 0x00000000b774d753, 1, 0)
print('added break %s with SIM_breakpoint' % bp1)
proc_hap = SIM_hap_add_callback_index("Core_Breakpoint_Memop", theHap, cpu, bp1)
print('Hap set on breakpoint %d' % bp1)

bp2 = SIM_run_command('bp.memory.break 0x00000000b774d75d')
print('added break %s with bp.memory.break' % bp2)
proc_hap = SIM_hap_add_callback_index("Core_Breakpoint_Memop", theHap, cpu, bp2)
print('Hap set on breakpoint %d' % bp2)

Results in:

   simics> run-script prefix.py
   Our cpu is ubuntu.mb.cpu0.core[0][0]
   added break 1 with SIM_breakpoint
   Hap set on breakpoint 1
   added break 1 with bp.memory.break
   Hap set on breakpoint 1
   NIL
   simics> c
   in theHap break 1 memory 0xb774d753
   in theHap break 1 memory 0xb774d753
   [ubuntu.cell_context] Breakpoint 1: ubuntu.cell_context 'x' access to v:0xb774d75d len=3

Is there a low-level Simics Python API for setting breakpoints with prefixes?

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Share Improve this question Follow asked Feb 11 at 22:22 Mike ThompsonMike Thompson 522 bronze badges

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1 Answer 1

Sorted by: Reset to default 0

However, the bp.memory.break command uses the front end processor which is inefficent from within breakpoint-intensive scripts.

Why is this inefficient? BTW, the bp.memory.break takes optional object parameter that can be use to select the object to set a breakpoint on.

Using a mix of SIM_breakpoint (for efficiency) and bp.memory.break (to set a prefix) seems dangerous because the bp.manager and SIM_breakpoint are not exclusive on their use of breakpoint numbers.

Yes, it is true. The numbers assigned are not related.

Is there a low-level Python API in Simics for setting breakpoints with prefixes?

The functionality is not available as Python API but one can "manually" update sim->breakpoints attribute to set the required prefix. From Python the attribute is available as conf.sim.attr.breakpoints. One can get the documentation for the attribute with the help sim->breakpoints command.

is inefficent from within breakpoint-intensive scripts

I don't know your performance requirements and whether this Python code is a bottleneck but can note that rewriting related code in C can definitely give a performance boost.

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