SIS MP success

Jiri Gaisler jiri at
Wed Dec 12 16:20:48 UTC 2018

On 12/12/18 10:26 AM, Sebastian Huber wrote:
> ----- Am 12. Dez 2018 um 10:01 schrieb Jiri Gaisler jiri at
>> After implementing the interrupt broadcast function, and stop telling
>> the software that there are 5 cores in the system when there really only
>> are 4, all tests run fine ..:-)
> This sounds great.
>> I can run all SMP tests with a time slot
>> of 50 clocks except smpclock01.exe, which fails with:
>> *** TEST VERSION: 5.0.0.b7a1f9efadd928cda0f56123a1b6245b30b076fc-modified
>> *** TEST TOOLS: 7.4.0 20181206 (RTEMS 5, RSB
>> b4e80fb8e29c47fa970b5cdb815c26f1af4fd173, Newlib
>> 2ab57ad59bc35dafffa69cd4da5e228971de069f)
>> ../../../../../../rtems/c/src/../../testsuites/smptests/smpclock01/init.c:
>> 117 cpu_self->Watchdog.ticks == ticks + 1
>> IU in error mode (128)
>>  12095340  40012200  91d02000  ta  0
>> sis> q
> There could be an issue with the interrupt delivery after an interrupt enable. In the test source we have:
>   // At this point the clock interrupt is pending
>   rtems_interrupt_local_enable(level);
>   // Here the clock interrupt should be already processed, incrementing the tick
>   rtems_test_assert(cpu_self->Watchdog.ticks == ticks + 1);

I checked for interrupts only once per time slice, which broke the
program. I changed to check for interrupts on every instruction and
smpclock01 now works with any slice time.

>> Lowering the time slot to 15 clocks fixes this error and the test passes.
>> I will clean up my sources, and work a bit on improving breakpoint
>> handling and tracing. The MP function broke erc32 and leon2 support, so
>> I will fix that too. After that I can post a patch if anyone is
>> interested. Threaded simulation could come after that ...
> Nice, do you plan to submit this to the upstream GDB? Sounds like a lot of work to do this.

I have been thinking to abandon the old sis which is under sim/erc32 in
gdb, and create a new simulator under sim/sis or sim/sparc. The old name
(erc32) is a bit misleading anyway since we now emulate leon2 and leon3
also. I will offer the gdb maintainers a patch for this move and an
upgrade to mp. If they don't like it then I will maintain sis-mp outside
the gdb tree and provide a patch for RSB. It is easier to maintain the
whole directory, than incremental patches to existing code.

Note that the whole work on MP support is actually driven by RISC-V (!).
I have a RISC-V version of sis that I use with an RTEMS bsp for a
GRLIB/AMBA SOC with a RISC-V core. I want to move to RISC-V SMP so I
need a simulator to test the software. Being more familiar with SPARC, I
decided to first get MP simulation to work with LEON3, and then just
port the RISC-V emulation. I also thought that a LEON3 sis-mp could be
useful for the RTEMS community, which was an other reason to start with
SPARC and then move to RISC-V.


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