** Description changed:

  [Impact]
  
-  * A change of the build system has caused a configuration change
-    to be ignored. Due to that the defaults of the machine type are
-    no more correct.
+  * A change of the build system has caused a configuration change
+    to be ignored. Due to that the defaults of the machine type are
+    no more correct.
  
-  * The fix is trivial and ensures that the type is known when built
-    with meson
+  * With the default set (in hirsute) you no more needed -M microvm as an 
+    argument as this was the default. But by loosing this default upgrades
+    from there will fail to start the microvm now.
+  
+  * The fix is trivial and ensures that the type is known when built
+    with meson
  
  [Test Plan]
  
-  * Run this:
-    $ qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
+  * Run this:
+    $ qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  
-   That is the special reduced build for microvms. It currently reports
+   That is the special reduced build for microvms. It currently reports
  
-   microvm              microvm (i386)
-   pc-i440fx-hirsute    Ubuntu 21.04 PC (i440FX + PIIX, 1996) (default)
+   microvm              microvm (i386)
+   pc-i440fx-hirsute    Ubuntu 21.04 PC (i440FX + PIIX, 1996) (default)
  
-   But it should report
+   But it should report
  
-   microvm              microvm (i386) (default)
- 
+   microvm              microvm (i386) (default)
  
  [Where problems could occur]
  
-  * Of the many things that qemu does this only affects qemu-system-x86_64- 
-    microvm which is a special build
-    (https://cpaelzer.github.io/blogs/009-microvm-in-ubuntu/)
-    So the use cases of that could be affected.
+  * Of the many things that qemu does this only affects qemu-system-x86_64-
+    microvm which is a special build
+    (https://cpaelzer.github.io/blogs/009-microvm-in-ubuntu/)
+    So the use cases of that could be affected.
  
  [Other Info]
-  
-  * Usually examples list to specify the type explicitly, and everyone 
-    doing so did not have a problem due to that missed default type.
  
+  * Usually examples list to specify the type explicitly, and everyone
+    doing so did not have a problem due to that missed default type.
  
  ---
  
  In Focal microvm worked and it was a fine addition for those that wanted
  to try this approach (mature solution of qemu/kvm reduced for a specific
  use case) to minimal VMs compared to the new projects (very use-case
  dedicated, but therefore missing quite some features) that spawned.
  
  But it turns out the configuration to make it a default is broken since
  qemu 5.2.
  
  Correct (Focal)
  root@f:~# qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  microvm              microvm (i386) (default)
  
  Broken (Groovy and later)
  root@i-kvm:~# qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  microvm              microvm (i386)
  pc-i440fx-impish     Ubuntu 21.10 PC (i440FX + PIIX, 1996) (default)
  
  If you follow the guide
    https://cpaelzer.github.io/blogs/009-microvm-in-ubuntu/
  It is still usable and that might explain why - even not being the prime use 
case - we had zero reports of this so far.
  The reason for the latter is that explicitly stating -M microvm (common) 
overcomes the issue and so do a few combinations with -nodefaults.
  
  Thanks to Michael Torkaev for spotting and also fixing this.
  But we should backport this as an SRU.
  
  TODOs to call this bug fixed:
  - add a testcase to the regression tests
  - SRU the fix

** Description changed:

  [Impact]
  
   * A change of the build system has caused a configuration change
     to be ignored. Due to that the defaults of the machine type are
     no more correct.
  
-  * With the default set (in hirsute) you no more needed -M microvm as an 
-    argument as this was the default. But by loosing this default upgrades
-    from there will fail to start the microvm now.
-  
+  * With the default set (in hirsute) you no more needed -M microvm as an
+    argument as this was the default. But by losing this default upgrades
+    from there will fail to start the microvm now.
+ 
   * The fix is trivial and ensures that the type is known when built
     with meson
  
  [Test Plan]
  
   * Run this:
     $ qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  
    That is the special reduced build for microvms. It currently reports
  
    microvm              microvm (i386)
    pc-i440fx-hirsute    Ubuntu 21.04 PC (i440FX + PIIX, 1996) (default)
  
    But it should report
  
    microvm              microvm (i386) (default)
  
  [Where problems could occur]
  
   * Of the many things that qemu does this only affects qemu-system-x86_64-
     microvm which is a special build
     (https://cpaelzer.github.io/blogs/009-microvm-in-ubuntu/)
     So the use cases of that could be affected.
  
  [Other Info]
  
   * Usually examples list to specify the type explicitly, and everyone
     doing so did not have a problem due to that missed default type.
  
  ---
  
  In Focal microvm worked and it was a fine addition for those that wanted
  to try this approach (mature solution of qemu/kvm reduced for a specific
  use case) to minimal VMs compared to the new projects (very use-case
  dedicated, but therefore missing quite some features) that spawned.
  
  But it turns out the configuration to make it a default is broken since
  qemu 5.2.
  
  Correct (Focal)
  root@f:~# qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  microvm              microvm (i386) (default)
  
  Broken (Groovy and later)
  root@i-kvm:~# qemu-system-x86_64-microvm -M ? | grep -e 'default' -e 'microvm'
  microvm              microvm (i386)
  pc-i440fx-impish     Ubuntu 21.10 PC (i440FX + PIIX, 1996) (default)
  
  If you follow the guide
    https://cpaelzer.github.io/blogs/009-microvm-in-ubuntu/
  It is still usable and that might explain why - even not being the prime use 
case - we had zero reports of this so far.
  The reason for the latter is that explicitly stating -M microvm (common) 
overcomes the issue and so do a few combinations with -nodefaults.
  
  Thanks to Michael Torkaev for spotting and also fixing this.
  But we should backport this as an SRU.
  
  TODOs to call this bug fixed:
  - add a testcase to the regression tests
  - SRU the fix

-- 
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1936894

Title:
  microvm is not the default type for qemu-system-x86_64-microvm
  >=qemu5.2

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