Re: [PATCH manager v3] fix #4503: ui: qemu: add detect zeroes disk option

[David Riley <d.riley@proxmox.com>]

On 6/18/26 1:49 PM, Lukas Sichert wrote:
> When discard is enabled, qemu-server defaults to 'detect-zeroes=unmap'.
> This can have a significant performance impact for zero writes on some
> setups, while users might still want to keep guest discard/TRIM support
> enabled.
>
> Allow configuring the option independently so 'discard' can stay enabled
> while zero detection is disabled. Persist the checkbox state explicitly,
> as the backend treats an absent value as default-enabled behavior,
> resulting in 'detect-zeroes=unmap' when 'discard' is enabled.

Thanks for submitting this patch.

While it clearly addresses the performance issues reported in #4503
[0], I was reading through the Bugzilla thread and noticed a request
to support the third QEMU state for detect_zeroes [1]. Currently, the
underlying parameter supports off, on, and unmap [2].

Since we are already modifying this configuration in the UI, it might
make sense to fully expose all three options to the user rather than
just a binary toggle as there is a difference between "on" and
"unmap".

[0] https://bugzilla.proxmox.com/show_bug.cgi?id=4503
[1] https://bugzilla.proxmox.com/show_bug.cgi?id=4503#c8
[2] https://www.qemu.org/docs/master/interop/qemu-storage-daemon-qmp-ref.html#enum-QSD-block-core.BlockdevDetectZeroesOptions

> Link: https://bugzilla.proxmox.com/show_bug.cgi?id=4503
> Signed-off-by: Lukas Sichert <l.sichert@proxmox.com>
> ---
>
> Notes:
>      changes from v2 to v3 (thanks @Fabian):
>      - add a comment explaining why this property is handled differently from
>        the others
>      
>      changes from v1 to v2:
>      - added bug-numer to commit header
>      - appended bug-link to commit body
>
>   www/manager6/qemu/HDEdit.js | 10 ++++++++++
>   1 file changed, 10 insertions(+)
>
> [...]
>