Re: [libvirt] [PATCHv2 04/10] libxl: fill HVM SDL and VNC settings based on <graphics/> entries

On Sat, Feb 07, 2015 at 12:22:51PM +0100, Marek Marczykowski-Górecki wrote: > On Thu, Feb 05, 2015 at 02:53:44PM -0700, Jim Fehlig wrote: > >> Marek Marczykowski-Górecki wrote: >> >>> Vfb entries in domain config are used only by PV drivers. Qemu >>> parameters are build based on b_info struct. So fill it with the same >>> data as vfb entries (actually the first one). >>> This will additionally allow graphic-less domain, when no <graphics/> >>> entries are present in domain XML (previously VNC was always enabled). >>> >>> >> This should already be handled in libxlMakeVfbList(). >> > Indeed, I've blindly rebased that patch from older version, but... > > >> Is there >> something missing in that function? >> > ... yes, if there is no graphics defined, the driver will set > b_info->u.hvm.nographic to 1. Which isn't enough to disable graphic, > because actual condition in libxl is: > if (info->nographic && (!info->sdl && !info->vnc)) { > flexarray_append(dm_args, "-nographic"); > } > > I'll think about some better solution (perhaps only part about initially setting > vnc and sdl to false?). > The problem is when domain XML contains no <video/> nor <graphics/> elements - libxl defaults then to setting up VNC (on 127.0.0.1). The solution here is to disable VNC/SDL and enable only when domain config says so. This still make VNC set when only <video/> is present (without <graphics type='vnc'/>), but at least there is a way make domain really headless. Below is patch which implement that approach. Note that it makes a big change in behaviour - it can make user's configuration broken (if he/she relied on this bug).

Disclaimer: I've tested it only with qemu in stubdomain.

-----8<----- From 37126eea6927f38fcb7f7f1190143fd7de54e9e6 Mon Sep 17 00:00:00 2001 From: Marek Marczykowski <marmarek(a)invisiblethingslab.com&gt; Date: Sun, 7 Apr 2013 19:48:03 +0200 Subject: [PATCH] libxl: disable VNC and SDL until explicitly enabled Cc: Marek Marczykowski-Górecki <marmarek(a)invisiblethingslab.com&gt; Otherwise when VM have no graphics defined, it is still enabled (with some libxl defaults).

Signed-off-by: Marek Marczykowski-Górecki <marmarek(a)invisiblethingslab.com&gt; --- src/libxl/libxl_conf.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/libxl/libxl_conf.c b/src/libxl/libxl_conf.c index 1811a83..7ee4e54 100644 --- a/src/libxl/libxl_conf.c +++ b/src/libxl/libxl_conf.c @@ -745,6 +745,10 @@ libxlMakeDomBuildInfo(virDomainDefPtr def, return -1; } + /* Disable VNC and SDL until explicitly enabled */ + libxl_defbool_set(&b_info->u.hvm.vnc.enable, 0); + libxl_defbool_set(&b_info->u.hvm.sdl.enable, 0);