Features/LegacyRemoval
Problem description
QEMU has a lot of interfaces (like command line options or HMP commands) and old features (like certain machine types) which are considered as deprecated since other more generic interfaces/features have been established instead. We likely don't want to carry the old code around forever. But we also do not want to remove it immediately to give the users and upper layer software stacks (like libvirt) a chance to migrate to the new interfaces step by step. So this page is about collecting information and ideas about which interfaces/features are considered as obsolete and when they should be removed.
Rules for removing an interface
Before an interface can be removed, there needs to be a clear transition plan for doing so. This means it should be added to this wiki page, and that there have to be at least two public releases of QEMU where the interface still works, but issues a warning when used. Two public releases are required so that the users have at least one development cycle to complain if they think that there is a good reason that the interface should not be removed. The warning should say that the interface is deprecated / going away soon, with a pointer to documentation or similar information about its replacement syntax.
Deprecated command line parameters
| Parameter | Rationale | Deprecated in | Removal in |
|---|---|---|---|
| -net channel | Replaced by "-netdev user,guestfwd=..."
(and is even not documented, i.e. hardly used in the wild) |
v2.6.0 | v3.0.0 |
| -smb | Replaced by "-netdev user,smb=..." | v2.6.0 | v3.0.0 ? |
| -tftp | Replaced by "-netdev user,tftp=..." | v2.6.0 | v3.0.0 ? |
| -bootp | Replaced by "-netdev user,bootfile=..." | v2.6.0 | v3.0.0 ? |
| -redir | Replaced by "-netdev user,hostfwd=..." | v2.6.0 | v3.0.0 ? |
| -usbdevice | Replaced by the generic -device parameter | not yet | ? |
Deprecated HMP commands
| Command | Rationale | Deprecated in | Removal in |
|---|---|---|---|
| host_net_add | Replaced by "netdev_add" | not yet | ? |
| host_net_remove | Replaced by "netdev_del" | 2.8 | ? |
| migrate_set_downtime, migrate_set_speed | Replaced by "migrate_set_parameter" | not yet | ? |
| migrate_set_downtime, migrate_set_speed | Replaced by "migrate_set_parameter" | 2.8 | ? |
Deprecated machines
| Machine | Rationale | Deprecated in | Removal in |
|---|---|---|---|
| prep (ppc) | Obsoleted by the "40p" machine | not yet | ? |
Miscellaneous
- Should we deprecate support for AIX and Solaris as host OS? (there is no build machine available for those)
- Should we deprecate the ia64 TCG backend?