Re: [Qemu-devel] [PATCH v1 0/4] Add feature to start QEMU without vhost-user backend

[Stefan Hajnoczi]

On Fri, May 29, 2015 at 01:42:26PM +0900, Tetsuya Mukawa wrote:
>    - Change user interface to be able to specify each feature by name.

I disagree with this change, the uint64_t backend_features option was
better because:

The text options will just result in a very long command-line that is
hard to read for humans.  Instead of checking a bit in a single hex
number, you have to scan over long comma-separated text options which
can be in any arbitrary order to find the feature bit you were looking
for.

This option needs to be scripted or generated by a management tool
anyway since it depends on the vhost-user backend program that is being
paired with QEMU.  The number of human users constructing these option
is extremely low - if they use it they'll copy-paste it from their
vhost-user program's documentation so the contents don't matter much
(shorter is better though).

The text options must be updated when new feature bits are added to
virtio-net.

For these reasons I find the numeric backend_features option better.

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