On 03/21/2017 10:26 PM, Joel Sherrill wrote: > > > On Tue, Mar 21, 2017 at 5:17 AM, Jiri Gaisler <j...@gaisler.se > <mailto:j...@gaisler.se>> wrote: > > The culprit seems to be the CASA instruction. The leon3 bsp is > built to always need this instruction, regardless if SMP is > enabled or not. The sis simulator does not support CASA at the > moment, hence the failures. The erc32 and leon2 bsp does not use > CASA since the hardware does not support it. If the leon3 bsp is > supposed to always require CASA, then it should be noted in the > bsp documentation as not all leon3 hardware actually supports CASA. > > > Hmmm... I let this sit so I could think. I wanted to make sure we didn't > head down a path of needing another BSP variant or multilib variant > unnecessarily. > > Where is this instruction used? I didn't see it in the port or BSP. But > again "grep -i cas" has a LOT of output. > > Do all SMP configurations have CASA? > > Is the instruction optional in uniprocessor configurations? If so, is > there a case where you must use it in uniprocessor configurations? > > Is this something in gcc (atomics?) that needs to be more conditional > on the CPU model? And.. could that push us to a multilib variant? > > Sorry for sounding confused. I just would like to understand when > the instruction is present and which knob settings we have to set > and how to know when it is OK to use. So it starts with knowing > when it is available in HW, when gcc might use it, etc.
The CASA (compare and swap) is present in the gcc multi-libbed libraries such as libatomic.a and libsupc++.a. The CASA is only present when the -mcpu=leon3 option is used, which is default for the leon3 bsp. So I think that it would be sufficient to note in the documentation that the default settings in the leon3 bsp requires support for CASA in the hardware. By removing -mcpu=leon3 from CPU_FLAGS in the leon3.cfg, the bsp can be built to work without CASA in the hardware. I have tested this, and some tests that previously failed (e.g. cdtest.exe) then worked OK on sis-leon3. I will however probably not work (well) with SMP. Other tests (e.g. sp69.exe) still fails on sis-leon3, but this is a problem in the leon3 port of sis and I am trying to fix it right now. To simplify testing in the future, I have added support for CASA to the leon3 port of sis. This makes it possible to test bsps both without CASA (erc32 & leon2) and with CASA (leon3). I will make new patches for sis once I have everything sorted... Jiri. > > Thanks. > > --joel > > Jiri. > > > On 03/19/2017 02:32 PM, Joel Sherrill wrote: >> Hi >> >> I was following up on Gedare's testing and tried leon3. There >> were a surprising number of failures there with SMP disabled. >> This is testing with gdb. Does anyone else get the same >> results with qemu or tsim? Any idea what's broken? >> >> >> Passed: 458 >> Failed: 20 >> Timeouts: 73 >> Invalid: 3 >> ------------- >> Total: 554 >> >> Failures: >> cdtest.exe >> spintrcritical20.exe >> dl05.exe >> spintrcritical01.exe >> spintrcritical04.exe >> spintrcritical10.exe >> spintrcritical22.exe >> sp69.exe >> spintrcritical21.exe >> sp11.exe >> spintrcritical16.exe >> spintrcritical23.exe >> psxfile01.exe >> spintrcritical05.exe >> spintrcritical02.exe >> spintrcritical08.exe >> psxgetrusage01.exe >> spcpucounter01.exe >> >> >> >> _______________________________________________ >> devel mailing list >> devel@rtems.org <mailto:devel@rtems.org> >> http://lists.rtems.org/mailman/listinfo/devel >> <http://lists.rtems.org/mailman/listinfo/devel> >
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