On 7/9/2026 8:03 AM, Pierrick Bouvier wrote:
> On 7/9/2026 7:52 AM, Alex Bennée wrote:
>> Pierrick Bouvier <[email protected]> writes:
>>
>>> Runs a record and replay test, and make sure the output produced by
>>> both runs is the same.
>>>
>>> Signed-off-by: Pierrick Bouvier <[email protected]>
>>> ---
>>>  tests/tcg/meson.build              |  1 +
>>>  tests/tcg/scripts/record_replay.sh | 16 ++++++++++++++++
>>>  2 files changed, 17 insertions(+)
>>>  create mode 100755 tests/tcg/scripts/record_replay.sh
>>>
>>> diff --git a/tests/tcg/meson.build b/tests/tcg/meson.build
>>> index 30178df0f7a..e610ce30f40 100644
>>> --- a/tests/tcg/meson.build
>>> +++ b/tests/tcg/meson.build
>>> @@ -7,6 +7,7 @@ if config_host.has_key('GDB')
>>>  endif
>>>  gdb = find_program(gdb_progs, required: false)
>>>  prog_gdb_test = find_program('../guest-debug/run-test.py')
>>> +prog_record_replay = find_program('./scripts/record_replay.sh')
>>>  prog_run_and_diff = find_program('./scripts/run_and_diff.sh')
>>>  prog_run_with_input = find_program('./scripts/run_with_input.sh')
>>>  prog_run_and_check_forbidden_output = find_program(
>>> diff --git a/tests/tcg/scripts/record_replay.sh 
>>> b/tests/tcg/scripts/record_replay.sh
>>> new file mode 100755
>>> index 00000000000..57775a2d4c1
>>> --- /dev/null
>>> +++ b/tests/tcg/scripts/record_replay.sh
>>> @@ -0,0 +1,16 @@
>>> +#!/usr/bin/env bash
>>
>> While at it is there any reason this couldn't be plain POSIX shell. I
>> don't think we explicitly require bash although its super likely to be
>> on most systems. configure is all POSIX shell.
>>
> 
> The main reason for me to use bash is that it supports set -uo pipefail
> in combination with set -e.
> 
> Which produces:
> - exit if a variable is undefined
> - exit if any command in a pipe sequence fails
> Without this, script shells are pretty much house of cards waiting to
> collapse on any corner case.
> 
> bash is available out of the box at least on macos, msys2, and I expect,
> every single linux distro out there. Not sure about bsds though.
> 
> If that's such a big issue, I can port the scripts to sh.
>

Interestingly, QEMU main Makefile makes bash a defacto requirement,
since it uses it for every single command to run. The reason is... to
use -o pipefail.

https://gitlab.com/qemu-project/qemu/-/blob/master/Makefile?ref_type=heads#L17

>>> +# SPDX-License-Identifier: GPL-2.0-or-later
>>> +
>>> +set -euo pipefail
>>> +
>>> +if [ $# -lt 2 ]; then
>>> +    echo "record_replay: qemu_bin [args]..." 1>&2
>>> +    exit 1
>>> +fi
>>> +qemu="$1";shift
>>> +tmp=$(mktemp -d)
>>> +trap "rm -rf $tmp" EXIT
>>> +set -x
>>> +$qemu -icount shift=5,rr=record,rrfile=$tmp/rr.bin "$@" |& tee $tmp/record
>>> +$qemu -icount shift=5,rr=replay,rrfile=$tmp/rr.bin "$@" |& tee $tmp/replay
>>> +diff $tmp/record $tmp/replay
>>
> 


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