id = 1606
title = "riscv: fence.i is not functional"
state = "opened"
created_at = "2023-04-17T17:03:39.906Z"
closed_at = "n/a"
labels = ["target: riscv"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/1606"
host-os = "Ubuntu 22.04.2 LTS"
host-arch = "x86"
qemu-version = "7.2.94 (v8.0.0-rc4)"
guest-os = "Ubuntu 22.04.2 LTS"
guest-arch = "RISC-V (riscv64-softmmu)"
description = """The attached user-level test is designed to do the following (in iteration):

  - Thread P0 on CPU0 changes some text/code, while

  - Thread P1 on CPU1 checks/reads the code, fence.i, then executes the same code.

Results (in stdout) indicates that CPU1 has read the new code (1:x5=a009) but executed the old one (1:x7=1) (against the specification)."""
reproduce = """1. echo 2 > /proc/sys/vm/nr_hugepages
2. ./CoRF+fence.i"""
additional = """Example output:
```[CoRF+fence.i.c](/uploads/c150ca0910783cc4bfc3886789b64c28/CoRF+fence.i.c)
Test CoRF+fence.i Allowed
Histogram (4 states)
25784  :>1:x5=0xa009; 1:x7=2;
24207  *>1:x5=0xa009; 1:x7=1;   <--  THIS LINE
8      :>1:x5=0xa019; 1:x7=1;
1      :>1:x5=0xa019; 1:x7=2;
Ok
Witnesses
Positive: 24207 Negative 25793
Condition exists (1:x5=0xa009 /\\ 1:x7=1) is  validated
Observation CoRF+fence.i Sometimes 24207 25793
Time CoRF+fence.i 0.85
Hash=
```"""