RISC-V Disassembler/translator instruction decoding disagreement

[Floyd42]

When running QEMU V3.1.0 for platform RISC-V, 64bit, Spike V1.10 with "-d in_asm -singlestep -D qemu_log.txt", my (faulty) test code brought up this message in the logs:

  0x000000008002cade: 051300009517e2bf illegal
  Disassembler disagrees with translator over instruction decoding
  Please report this to <email address hidden>

You may want to resolve the disagreement.

Axel

[Bastian Koppelmann (kbastian)]

Hi Axel,

can you link us to your test code, such that we can try to reproduce it.

Cheers,
Bastian

[Floyd42 (axelheider)]

Sorry, I don't have the test code, since this was created by a memory corruption. However, the way I understand the message is, that there is some internal disagreement how to decode the op-code "051300009517e2bf" - which mige be an invalid opcode anyway. So a simple test application would just consist of this opcode.

[Peter Maydell (pmaydell)]

I've encountered this message before for invalid instructions, and it often doesn't really mean there was an error. In particular for variable instruction length ISAs you'll see the error if the translator reads part of the insn and determines that it's invalid without needing to read the rest of it -- https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg06845.html talks about a case of that for x86.

[Thomas Huth (th-huth)]

The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now.
If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience.

[Thomas Huth (th-huth)]

This is an automated cleanup. This bug report has been moved
to QEMU's new bug tracker on gitlab.com and thus gets marked
as 'expired' now. Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/53