Re: [libvirt] [PATCH v2 2/6] virsh: add support for VIR_DOMAIN_CONSOLE_FORCE flag
On 12/07/2011 11:08 AM, Peter Krempa wrote:
This patch adds support for the newly introduced VIR_DOMAIN_CONSOLE
s/$/_FORCE/
flag. The console command now has an optional parameter --force that
specifies that the user wants to forcibly interrupt an ongoing console
session and create a new one. The behaviour to this point was, that the
s/,//
daemon openend two streams to the console, that competed for data
from
s/openend/opened/
the pipe and the result was, that both of the consoles ended up
s/pipe and the result was,/pipe, and the result was/
scrambled.
* tools/console.c:
- add support for flag passthrough
* tools/console.h:
- modify function prototypes to match impl.
* tools/virsh.c:
- add flag --force for the console command
---
tools/console.c | 5 +++--
tools/console.h | 3 ++-
tools/virsh.c | 18 +++++++++++++-----
3 files changed, 18 insertions(+), 8 deletions(-)
+++ b/tools/virsh.c
@@ -787,11 +787,14 @@ static const vshCmdInfo info_console[] = {
static const vshCmdOptDef opts_console[] = {
{"domain", VSH_OT_DATA, VSH_OFLAG_REQ, N_("domain name, id or
uuid")},
{"devname", VSH_OT_STRING, 0, N_("character device name")},
+ {"force", VSH_OT_BOOL, 0, N_("force console connection (disconnect
already connected sessions)")},
Might want to wrap this to fit 80 columns.
@@ -834,7 +839,10 @@ cmdConsole(vshControl *ctl, const vshCmd *cmd)
goto cleanup;
}
- ret = cmdRunConsole(ctl, dom, name);
+ if (force)
+ flags = VIR_DOMAIN_CONSOLE_FORCE;
Okay as-is, but if we add more flags in the future, this is not
maintainer-friendly. I'd use |= instead of = so this line won't need
future edits.
ACK.
Hmm, wondering about back-compat - what happens if we are talking to an
older libvirt that does not know VIR_DOMAIN_CONSOLE_FORCE, but also
which does not prevent multiple connections when flags==0? At first
glance, it looks like we're stuck - there's no useful way to tell if a
console was already in use.
But maybe we could add a new API, to allow probing whether a console is
in use. If the API exists, then we know whether the console is in use
(and we also know whether --force will work); if the API does not exist,
the we know we are talking to an older server that multiplexes
connections. Maybe we should have:
virsh console domain --safe => refuse to connect unless connection is
safe (fails on older servers)
virsh console domain --force => force connection (fails on older servers)
virsh console domain => existing behavior (connects on older servers,
even if it corrupts connection, and safely connects on newer servers)
that is, I'm thinking it might be worth it to add a new --safe option
that lets the user probe (via a new API virDomainConsoleInUse(dom,
dev_name, flags)) whether the attempt will be safe.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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