[PATCH v4 0/6] Enable more iotests during "make check-block"

[PATCH v4 0/6] Enable more iotests during "make check-block"

[Thomas Huth]

As discussed here:

 https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg00697.html

and here:

 https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg01388.html

it would be good to have some more valuable iotests enabled in the
"auto" group to get better iotest coverage during "make check".

Since these Python-based tests require a QEMU that features a 'virtio-blk'
device, we can only run the Python tests if this device is available. With
binaries like qemu-system-tricore, the Python-based tests will be skipped.

v4:
 - The check for 'virtio-blk' is now done in the tests/qemu-iotests/check
   script instead of tests/check-block.sh (to avoid to duplicate the code
   that searches for the right QEMU binary - and we can also still run
   the shell-based tests this way).
 - Added the new patch to check for the availability of virtio devices in
   the iotests 127 and 267.
 - The patch that drops test 130 from the "auto" group has already been
   merged and thus been dropped from this series.

v3:
 - Test 183 fails on Patchew, so I removed it from the "auto" group
   again

v2:
 - Checked the iotests with NetBSD, too (now that Eduardo has
   re-activated Gerd's patches for creating NetBSD VM images)
 - Use 'openbsd' instead of 'openbsd6'
 - Use 'grep -q' instead of 'grep' for grep'ing silently
 - Added the patch to disable 130 from the "auto" group


John Snow (1):
  iotests: remove 'linux' from default supported platforms

Thomas Huth (5):
  iotests: Test 041 only works on certain systems
  iotests: Test 183 does not work on macOS and OpenBSD
  iotests: Check for the availability of the required devices in 267 and
    127
  iotests: Skip Python-based tests if QEMU does not support virtio-blk
  iotests: Enable more tests in the 'auto' group to improve test
    coverage

 tests/qemu-iotests/041        |  3 ++-
 tests/qemu-iotests/127        |  2 ++
 tests/qemu-iotests/183        |  1 +
 tests/qemu-iotests/267        |  2 ++
 tests/qemu-iotests/check      |  8 ++++++--
 tests/qemu-iotests/common.rc  | 14 ++++++++++++++
 tests/qemu-iotests/group      | 14 +++++++-------
 tests/qemu-iotests/iotests.py | 16 +++++++++++-----
 8 files changed, 45 insertions(+), 15 deletions(-)

-- 
2.18.1

[PATCH v4 1/6] iotests: remove 'linux' from default supported platforms

[Thomas Huth]

From: John Snow <jsnow@redhat.com>

verify_platform will check an explicit whitelist and blacklist instead.
The default will now be assumed to be allowed to run anywhere.

For tests that do not specify their platforms explicitly, this has the effect of
enabling these tests on non-linux platforms. For tests that always specified
linux explicitly, there is no change.

For Python tests on FreeBSD at least; only seven python tests fail:
045 147 149 169 194 199 211

045 and 149 appear to be misconfigurations,
147 and 194 are the AF_UNIX path too long error,
169 and 199 are bitmap migration bugs, and
211 is a bug that shows up on Linux platforms, too.

This is at least good evidence that these tests are not Linux-only. If
they aren't suitable for other platforms, they should be disabled on a
per-platform basis as appropriate.

Therefore, let's switch these on and deal with the failures.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/iotests.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index df0708923d..de8b904d87 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -896,9 +896,14 @@ def verify_protocol(supported=[], unsupported=[]):
     if not_sup or (imgproto in unsupported):
         notrun('not suitable for this protocol: %s' % imgproto)
 
-def verify_platform(supported_oses=['linux']):
-    if True not in [sys.platform.startswith(x) for x in supported_oses]:
-        notrun('not suitable for this OS: %s' % sys.platform)
+def verify_platform(supported=None, unsupported=None):
+    if unsupported is not None:
+        if any((sys.platform.startswith(x) for x in unsupported)):
+            notrun('not suitable for this OS: %s' % sys.platform)
+
+    if supported is not None:
+        if not any((sys.platform.startswith(x) for x in supported)):
+            notrun('not suitable for this OS: %s' % sys.platform)
 
 def verify_cache_mode(supported_cache_modes=[]):
     if supported_cache_modes and (cachemode not in supported_cache_modes):
@@ -989,7 +994,8 @@ def execute_unittest(output, verbosity, debug):
             sys.stderr.write(out)
 
 def execute_test(test_function=None,
-                 supported_fmts=[], supported_oses=['linux'],
+                 supported_fmts=[],
+                 supported_platforms=None,
                  supported_cache_modes=[], unsupported_fmts=[],
                  supported_protocols=[], unsupported_protocols=[]):
     """Run either unittest or script-style tests."""
@@ -1006,7 +1012,7 @@ def execute_test(test_function=None,
     verbosity = 1
     verify_image_format(supported_fmts, unsupported_fmts)
     verify_protocol(supported_protocols, unsupported_protocols)
-    verify_platform(supported_oses)
+    verify_platform(supported=supported_platforms)
     verify_cache_mode(supported_cache_modes)
 
     if debug:
-- 
2.18.1

[PATCH v4 2/6] iotests: Test 041 only works on certain systems

[Thomas Huth]

041 works fine on Linux, FreeBSD, NetBSD and OpenBSD, but fails on macOS.
Let's mark it as only supported on the systems where we know that it is
working fine.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qemu-iotests/041 | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 8568426311..0326888c98 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -1123,4 +1123,5 @@ class TestOrphanedSource(iotests.QMPTestCase):
 
 if __name__ == '__main__':
     iotests.main(supported_fmts=['qcow2', 'qed'],
-                 supported_protocols=['file'])
+                 supported_protocols=['file'],
+                 supported_platforms=['linux', 'freebsd', 'netbsd', 'openbsd'])
-- 
2.18.1

[PATCH v4 3/6] iotests: Test 183 does not work on macOS and OpenBSD

[Thomas Huth]

In the long term, we might want to add test 183 to the "auto" group
(but it still fails occasionally, so we cannot do that yet). However,
when running 183 in Cirrus-CI on macOS, or with our vm-build-openbsd
target, it currently always fails with an "Timeout waiting for return
on handle 0" error.

Let's mark it as supported only on systems where the test is working
fine (i.e. Linux, FreeBSD and NetBSD).

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qemu-iotests/183 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/qemu-iotests/183 b/tests/qemu-iotests/183
index bced83fae0..0bbae13647 100755
--- a/tests/qemu-iotests/183
+++ b/tests/qemu-iotests/183
@@ -42,6 +42,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 . ./common.filter
 . ./common.qemu
 
+_supported_os Linux FreeBSD NetBSD
 _supported_fmt qcow2 raw qed quorum
 _supported_proto file
 
-- 
2.18.1

[PATCH v4 4/6] iotests: Check for the availability of the required devices in 267 and 127

[Thomas Huth]

We are going to enable 127 in the "auto" group, but it only works if
virtio-scsi and scsi-hd are available - which is not the case with
QEMU binaries like qemu-system-tricore for example, so we need a
proper check for the availability of these devices here.

A very similar problem exists in iotest 267 - it has been added to
the "auto" group already, but requires virtio-blk and thus currently
fails with qemu-system-tricore for example. Let's also add aproper
check there.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qemu-iotests/127       |  2 ++
 tests/qemu-iotests/267       |  2 ++
 tests/qemu-iotests/common.rc | 14 ++++++++++++++
 3 files changed, 18 insertions(+)

diff --git a/tests/qemu-iotests/127 b/tests/qemu-iotests/127
index b64926ab31..a4fc866038 100755
--- a/tests/qemu-iotests/127
+++ b/tests/qemu-iotests/127
@@ -43,6 +43,8 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
 _supported_fmt qcow2
 _supported_proto file
 
+_require_devices virtio-scsi scsi-hd
+
 IMG_SIZE=64K
 
 _make_test_img $IMG_SIZE
diff --git a/tests/qemu-iotests/267 b/tests/qemu-iotests/267
index 170e173c0a..17ac640a83 100755
--- a/tests/qemu-iotests/267
+++ b/tests/qemu-iotests/267
@@ -44,6 +44,8 @@ _supported_os Linux
 # Internal snapshots are (currently) impossible with refcount_bits=1
 _unsupported_imgopts 'refcount_bits=1[^0-9]'
 
+_require_devices virtio-blk
+
 do_run_qemu()
 {
     echo Testing: "$@"
diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index 0cc8acc9ed..38e949cf69 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -643,5 +643,19 @@ _require_drivers()
     done
 }
 
+# Check that a set of devices is available in the QEMU binary
+#
+_require_devices()
+{
+    available=$($QEMU -M none -device help | \
+                grep ^name | sed -e 's/^name "//' -e 's/".*$//')
+    for device
+    do
+        if ! echo "$available" | grep -q "$device" ; then
+            _notrun "$device not available"
+        fi
+    done
+}
+
 # make sure this script returns success
 true
-- 
2.18.1

[PATCH v4 5/6] iotests: Skip Python-based tests if QEMU does not support virtio-blk

[Thomas Huth]

We are going to enable some of the python-based tests in the "auto" group,
and these tests require virtio-blk to work properly. Running iotests
without virtio-blk likely does not make too much sense anyway, so instead
of adding a check for the availability of virtio-blk to each and every
test (which does not sound very appealing), let's rather add a check for
this a central spot in the "check" script instead (so that it is still
possible to run "make check" for qemu-system-tricore for example).

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qemu-iotests/check | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
index 90970b0549..bce3035d5a 100755
--- a/tests/qemu-iotests/check
+++ b/tests/qemu-iotests/check
@@ -642,7 +642,11 @@ fi
 python_usable=false
 if $PYTHON -c 'import sys; sys.exit(0 if sys.version_info >= (3,6) else 1)'
 then
-    python_usable=true
+    # Our python framework also requires virtio-blk
+    if "$QEMU_PROG" -M none -device help | grep -q virtio-blk >/dev/null 2>&1
+    then
+        python_usable=true
+    fi
 fi
 
 default_machine=$($QEMU_PROG -machine help | sed -n '/(default)/ s/ .*//p')
@@ -830,7 +834,7 @@ do
                 run_command="$PYTHON $seq"
             else
                 run_command="false"
-                echo "Unsupported Python version" > $seq.notrun
+                echo "Unsupported Python version or missing virtio-blk" > $seq.notrun
             fi
         else
             run_command="./$seq"
-- 
2.18.1

[PATCH v4 6/6] iotests: Enable more tests in the 'auto' group to improve test coverage

[Thomas Huth]

According to Kevin, tests 030, 040 and 041 are among the most valuable
tests that we have, so we should always run them if possible, even if
they take a little bit longer.

According to Max, it would be good to have a test for iothreads and
migration. 127 and 256 seem to be good candidates for iothreads. For
migration, let's enable 181 and 203 (which also tests iothreads).
(091 would be a good candidate for migration, too, but Alex Bennée
reported that this test fails on ZFS file systems, so it can't be
included yet)

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qemu-iotests/group | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 6b10a6a762..2b56392e31 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -51,7 +51,7 @@
 027 rw auto quick
 028 rw backing quick
 029 rw auto quick
-030 rw backing
+030 rw auto backing
 031 rw auto quick
 032 rw auto quick
 033 rw auto quick
@@ -61,8 +61,8 @@
 037 rw auto backing quick
 038 rw auto backing quick
 039 rw auto quick
-040 rw
-041 rw backing
+040 rw auto
+041 rw auto backing
 042 rw auto quick
 043 rw auto backing
 044 rw
@@ -148,7 +148,7 @@
 124 rw backing
 125 rw
 126 rw auto backing
-127 rw backing quick
+127 rw auto backing quick
 128 rw quick
 129 rw quick
 130 rw quick
@@ -197,7 +197,7 @@
 177 rw auto quick
 178 img
 179 rw auto quick
-181 rw migration
+181 rw auto migration
 182 rw quick
 183 rw migration
 184 rw auto quick
@@ -218,7 +218,7 @@
 200 rw
 201 rw migration
 202 rw quick
-203 rw migration
+203 rw auto migration
 204 rw quick
 205 rw quick
 206 rw
@@ -270,7 +270,7 @@
 253 rw quick
 254 rw backing quick
 255 rw quick
-256 rw quick
+256 rw auto quick
 257 rw
 258 rw quick
 260 rw quick
-- 
2.18.1

Re: [PATCH v4 2/6] iotests: Test 041 only works on certain systems

[Max Reitz]

[-- Attachment #1.1: Type: text/plain, Size: 402 bytes --]

On 02.12.19 11:10, Thomas Huth wrote:
> 041 works fine on Linux, FreeBSD, NetBSD and OpenBSD, but fails on macOS.
> Let's mark it as only supported on the systems where we know that it is
> working fine.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/qemu-iotests/041 | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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Re: [PATCH v4 3/6] iotests: Test 183 does not work on macOS and OpenBSD

[Max Reitz]

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On 02.12.19 11:10, Thomas Huth wrote:
> In the long term, we might want to add test 183 to the "auto" group
> (but it still fails occasionally, so we cannot do that yet). However,
> when running 183 in Cirrus-CI on macOS, or with our vm-build-openbsd
> target, it currently always fails with an "Timeout waiting for return
> on handle 0" error.
> 
> Let's mark it as supported only on systems where the test is working
> fine (i.e. Linux, FreeBSD and NetBSD).
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/qemu-iotests/183 | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tests/qemu-iotests/183 b/tests/qemu-iotests/183
> index bced83fae0..0bbae13647 100755
> --- a/tests/qemu-iotests/183
> +++ b/tests/qemu-iotests/183
> @@ -42,6 +42,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
>  . ./common.filter
>  . ./common.qemu
>  
> +_supported_os Linux FreeBSD NetBSD

I don’t suppose you have data on OpenBSD?

(And maybe it would be best to let _unsupported_os just check whether
$HOSTOS contains any of these strings (ideally in a case-insensitive
way) instead of checking for equality, but that’s for another series to
decide.)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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Re: [PATCH v4 4/6] iotests: Check for the availability of the required devices in 267 and 127

[Max Reitz]

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On 02.12.19 11:10, Thomas Huth wrote:
> We are going to enable 127 in the "auto" group, but it only works if
> virtio-scsi and scsi-hd are available - which is not the case with
> QEMU binaries like qemu-system-tricore for example, so we need a
> proper check for the availability of these devices here.
> 
> A very similar problem exists in iotest 267 - it has been added to
> the "auto" group already, but requires virtio-blk and thus currently
> fails with qemu-system-tricore for example. Let's also add aproper
> check there.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/qemu-iotests/127       |  2 ++
>  tests/qemu-iotests/267       |  2 ++
>  tests/qemu-iotests/common.rc | 14 ++++++++++++++
>  3 files changed, 18 insertions(+)

Reviewed-by: Max Reitz <mreitz@redhat.com>


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Re: [PATCH v4 5/6] iotests: Skip Python-based tests if QEMU does not support virtio-blk

[Max Reitz]

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On 02.12.19 11:10, Thomas Huth wrote:
> We are going to enable some of the python-based tests in the "auto" group,
> and these tests require virtio-blk to work properly. Running iotests
> without virtio-blk likely does not make too much sense anyway, so instead
> of adding a check for the availability of virtio-blk to each and every
> test (which does not sound very appealing), let's rather add a check for
> this a central spot in the "check" script instead (so that it is still
> possible to run "make check" for qemu-system-tricore for example).
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/qemu-iotests/check | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
> index 90970b0549..bce3035d5a 100755
> --- a/tests/qemu-iotests/check
> +++ b/tests/qemu-iotests/check
> @@ -642,7 +642,11 @@ fi
>  python_usable=false
>  if $PYTHON -c 'import sys; sys.exit(0 if sys.version_info >= (3,6) else 1)'
>  then
> -    python_usable=true
> +    # Our python framework also requires virtio-blk
> +    if "$QEMU_PROG" -M none -device help | grep -q virtio-blk >/dev/null 2>&1
> +    then
> +        python_usable=true
> +    fi
>  fi
>  
>  default_machine=$($QEMU_PROG -machine help | sed -n '/(default)/ s/ .*//p')
> @@ -830,7 +834,7 @@ do
>                  run_command="$PYTHON $seq"
>              else
>                  run_command="false"
> -                echo "Unsupported Python version" > $seq.notrun
> +                echo "Unsupported Python version or missing virtio-blk" > $seq.notrun

A $python_unusable_because might be helpful (set in to-be-added else
branches for the ifs that set python_usable to true), but either way:

Reviewed-by: Max Reitz <mreitz@redhat.com>

>              fi
>          else
>              run_command="./$seq"
> 



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Re: [PATCH v4 6/6] iotests: Enable more tests in the 'auto' group to improve test coverage

[Max Reitz]

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On 02.12.19 11:10, Thomas Huth wrote:
> According to Kevin, tests 030, 040 and 041 are among the most valuable
> tests that we have, so we should always run them if possible, even if
> they take a little bit longer.
> 
> According to Max, it would be good to have a test for iothreads and
> migration. 127 and 256 seem to be good candidates for iothreads. For
> migration, let's enable 181 and 203 (which also tests iothreads).
> (091 would be a good candidate for migration, too, but Alex Bennée
> reported that this test fails on ZFS file systems, so it can't be
> included yet)
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/qemu-iotests/group | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
> index 6b10a6a762..2b56392e31 100644
> --- a/tests/qemu-iotests/group
> +++ b/tests/qemu-iotests/group
> @@ -51,7 +51,7 @@

Reviewed-by: Max Reitz <mreitz@redhat.com>


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Re: [PATCH v4 0/6] Enable more iotests during "make check-block"

[Max Reitz]

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On 02.12.19 11:10, Thomas Huth wrote:
> As discussed here:
> 
>  https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg00697.html
> 
> and here:
> 
>  https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg01388.html
> 
> it would be good to have some more valuable iotests enabled in the
> "auto" group to get better iotest coverage during "make check".
> 
> Since these Python-based tests require a QEMU that features a 'virtio-blk'
> device, we can only run the Python tests if this device is available. With
> binaries like qemu-system-tricore, the Python-based tests will be skipped.
> 
> v4:
>  - The check for 'virtio-blk' is now done in the tests/qemu-iotests/check
>    script instead of tests/check-block.sh (to avoid to duplicate the code
>    that searches for the right QEMU binary - and we can also still run
>    the shell-based tests this way).
>  - Added the new patch to check for the availability of virtio devices in
>    the iotests 127 and 267.
>  - The patch that drops test 130 from the "auto" group has already been
>    merged and thus been dropped from this series.

Looks good to me, the only question is whether you’d like to add a
$python_unusable_because in patch 5 or not.

Max


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Re: [PATCH v4 3/6] iotests: Test 183 does not work on macOS and OpenBSD

[Thomas Huth]

On 20/01/2020 15.36, Max Reitz wrote:
> On 02.12.19 11:10, Thomas Huth wrote:
>> In the long term, we might want to add test 183 to the "auto" group
>> (but it still fails occasionally, so we cannot do that yet). However,
>> when running 183 in Cirrus-CI on macOS, or with our vm-build-openbsd
>> target, it currently always fails with an "Timeout waiting for return
>> on handle 0" error.
>>
>> Let's mark it as supported only on systems where the test is working
>> fine (i.e. Linux, FreeBSD and NetBSD).
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  tests/qemu-iotests/183 | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/tests/qemu-iotests/183 b/tests/qemu-iotests/183
>> index bced83fae0..0bbae13647 100755
>> --- a/tests/qemu-iotests/183
>> +++ b/tests/qemu-iotests/183
>> @@ -42,6 +42,7 @@ trap "_cleanup; exit \$status" 0 1 2 3 15
>>  . ./common.filter
>>  . ./common.qemu
>>  
>> +_supported_os Linux FreeBSD NetBSD
> 
> I don’t suppose you have data on OpenBSD?

I've checked it with our "make vm-build-openbsd" target (see patch
description) and it was failing there in the same way as on macOS.

> Reviewed-by: Max Reitz <mreitz@redhat.com>

Thanks!

 Thomas

Re: [PATCH v4 5/6] iotests: Skip Python-based tests if QEMU does not support virtio-blk

[Thomas Huth]

On 20/01/2020 15.50, Max Reitz wrote:
> On 02.12.19 11:10, Thomas Huth wrote:
>> We are going to enable some of the python-based tests in the "auto" group,
>> and these tests require virtio-blk to work properly. Running iotests
>> without virtio-blk likely does not make too much sense anyway, so instead
>> of adding a check for the availability of virtio-blk to each and every
>> test (which does not sound very appealing), let's rather add a check for
>> this a central spot in the "check" script instead (so that it is still
>> possible to run "make check" for qemu-system-tricore for example).
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  tests/qemu-iotests/check | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
>> index 90970b0549..bce3035d5a 100755
>> --- a/tests/qemu-iotests/check
>> +++ b/tests/qemu-iotests/check
>> @@ -642,7 +642,11 @@ fi
>>  python_usable=false
>>  if $PYTHON -c 'import sys; sys.exit(0 if sys.version_info >= (3,6) else 1)'
>>  then
>> -    python_usable=true
>> +    # Our python framework also requires virtio-blk
>> +    if "$QEMU_PROG" -M none -device help | grep -q virtio-blk >/dev/null 2>&1
>> +    then
>> +        python_usable=true
>> +    fi
>>  fi
>>  
>>  default_machine=$($QEMU_PROG -machine help | sed -n '/(default)/ s/ .*//p')
>> @@ -830,7 +834,7 @@ do
>>                  run_command="$PYTHON $seq"
>>              else
>>                  run_command="false"
>> -                echo "Unsupported Python version" > $seq.notrun
>> +                echo "Unsupported Python version or missing virtio-blk" > $seq.notrun
> 
> A $python_unusable_because might be helpful (set in to-be-added else
> branches for the ifs that set python_usable to true), but either way:

Sounds like a good idea, I'll give it a try and send a v5.

 Thanks,
  Thomas