bug#47780: [installer] Trying to install to DVD leads to crash

bug#47780: [installer] Trying to install to DVD leads to crash

[Ludovic Courtès]

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Hello!

I’ve run an installation with:

  qemu-img create -f qcow2  /tmp/img.qcow2 2G
  qemu-system-x86_64 -enable-kvm -m 2048 \
    -cdrom /gnu/store/…-image.iso -hda /tmp/img.qcow2 \
    -boot d

where the image was obtained by running:

  guix system disk-image -t iso9660 --label=GUIX_x86_64-linux_1.2.1 \
    gnu/system/install.scm

The installer would propose me two target storage devices: hard disk and
CD/DVD.  I mistakenly chose the latter, which led to a crash (screenshot
attached).

Possible improvements are:

  1. gracefully handling this error;
  2. filtering out read-only storage devices from the menu.

Thoughts?

(This is with commit 863bd265e458d2761906770802716555c54e69a4.)

Ludo’.


[-- Attachment #2: the crash --]
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bug#47780: [installer] Trying to install to DVD leads to crash

[Mathieu Othacehe]

Hello Ludo,

> Possible improvements are:
>
>   1. gracefully handling this error;
>   2. filtering out read-only storage devices from the menu.
>
> Thoughts?

Thanks to David's help[1], I realized that the non-filtering of the
installation device was causing some of the (uuid->string #f) issues
users were experimenting.

With this commit: 154a4e046281c28e39b5016e965d3d937a2ea4a1, I improved
the install device detection by removing the device with the default
Guix System image ISO label.

Now this is fragile and won't work if the ISO label is modified like in
your use-case. I cannot find another reliable way to detect the
installation device in the "non-install-devices" procedure. Do you have
any better idea?

Thanks,

Mathieu

[1]: https://issues.guix.gnu.org/44872

bug#47780: [installer] Trying to install to DVD leads to crash

[Ludovic Courtès]

Hi,

Mathieu Othacehe <othacehe@gnu.org> skribis:

>> Possible improvements are:
>>
>>   1. gracefully handling this error;
>>   2. filtering out read-only storage devices from the menu.
>>
>> Thoughts?
>
> Thanks to David's help[1], I realized that the non-filtering of the
> installation device was causing some of the (uuid->string #f) issues
> users were experimenting.
>
> With this commit: 154a4e046281c28e39b5016e965d3d937a2ea4a1, I improved
> the install device detection by removing the device with the default
> Guix System image ISO label.

Nice.

> Now this is fragile and won't work if the ISO label is modified like in
> your use-case. I cannot find another reliable way to detect the
> installation device in the "non-install-devices" procedure. Do you have
> any better idea?

Does Parted provide a way to tell whether a storage device is read-only?
That would be ideal.

Thanks,
Ludo’.

bug#47780: [installer] Trying to install to DVD leads to crash

[Mathieu Othacehe]

Hey,

> Does Parted provide a way to tell whether a storage device is read-only?
> That would be ideal.

Yes it does, but this is not enough for a reliable installation device
detection. In Qemu the installation device is /dev/sr0 that is
reported as read-only by parted.

Using real hardware, and an installation device on an USB drive, the
installation device is /dev/sd* and is not reported as read-only by
parted.

However, I found a better way to detect the installation device, that
relies on reading the root partition UUID from the command line.

I combined the read-only parted method and the UUID based installation
device detection in e12be802e02b3345a753e7ec1287852a7337a0a5. This seems
to work well for all my machines, plus for your VM use case.

Closing this one,

Thanks,

Mathieu

bug#47780: [installer] Trying to install to DVD leads to crash

[Ludovic Courtès]

Hi,

Mathieu Othacehe <othacehe@gnu.org> skribis:

>> Does Parted provide a way to tell whether a storage device is read-only?
>> That would be ideal.
>
> Yes it does, but this is not enough for a reliable installation device
> detection. In Qemu the installation device is /dev/sr0 that is
> reported as read-only by parted.
>
> Using real hardware, and an installation device on an USB drive, the
> installation device is /dev/sd* and is not reported as read-only by
> parted.

I see.

> However, I found a better way to detect the installation device, that
> relies on reading the root partition UUID from the command line.
>
> I combined the read-only parted method and the UUID based installation
> device detection in e12be802e02b3345a753e7ec1287852a7337a0a5. This seems
> to work well for all my machines, plus for your VM use case.

That’s clever.  Thanks!

Ludo’.