Re: [libvirt] [PATCH v3 01/11] util: Introduce virHostGetDRMRenderNode helper

On Mon, Dec 03, 2018 at 03:18:47PM +0000, Daniel P. Berrangé wrote: > On Thu, Nov 29, 2018 at 03:20:11PM +0100, Erik Skultety wrote: > > This is the first step towards libvirt picking the first available > > render node instead of QEMU. It also makes sense for us to be able to do > > that, since we allow specifying the node directly for SPICE, so if > > there's no render node specified by the user, we should pick the first > > available one. The algorithm used for that is essentially the same as > > the one QEMU uses. > > > > Signed-off-by: Erik Skultety <eskultet(a)redhat.com&gt; > > --- > > src/libvirt_private.syms | 1 + > > src/util/virutil.c | 53 ++++++++++++++++++++++++++++++++++++++++ > > src/util/virutil.h | 2 ++ > > 3 files changed, 56 insertions(+) > > > > diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms > > index 5018a13e9c..c7f08f9620 100644 > > --- a/src/libvirt_private.syms > > +++ b/src/libvirt_private.syms > > @@ -3151,6 +3151,7 @@ virGetUserName; > > virGetUserRuntimeDirectory; > > virGetUserShell; > > virHexToBin; > > +virHostGetDRMRenderNode; > > virHostHasIOMMU; > > virIndexToDiskName; > > virIsDevMapperDevice; > > diff --git a/src/util/virutil.c b/src/util/virutil.c > > index 974cffc2ee..da12a11e04 100644 > > --- a/src/util/virutil.c > > +++ b/src/util/virutil.c > > @@ -2145,3 +2145,56 @@ virHostHasIOMMU(void) > > VIR_DIR_CLOSE(iommuDir); > > return ret; > > } > > + > > + > > +/** > > + * virHostGetDRMRenderNode: > > + * > > + * Picks the first DRM render node available. Missing DRI or missing DRM render > > + * nodes in the system results in an error. > > + * > > + * Returns an absolute path to the first render node available or NULL in case > > + * of an error with the error being reported. > > + * Caller is responsible for freeing the result string. > > + * > > + */ > > +char * > > +virHostGetDRMRenderNode(void) > > +{ > > + char *ret = NULL; > > + DIR *driDir = NULL; > > + const char *driPath = "/dev/dri"; > > + struct dirent *ent = NULL; > > + int dirErr = 0; > > + bool have_rendernode = false; > > + > > + if (virDirOpen(&driDir, driPath) < 0) > > + return NULL; > > + > > + while ((dirErr = virDirRead(driDir, &ent, driPath)) > 0) { > > + if (ent->d_type != DT_CHR) > > + continue; > > The 'd_type' field is a Linux-ism, so this has broken the build > > Is it even needed ? ie are then any files in /dev/dri that have > a prefix of "renderD" but which are not character devices ? Can't say it's impossible, but I haven't bumped into a setup like that - I had different permissions, I had DRI missing, I had renderD missing, but I haven't seen a non-character DRI node...You're right in the thinking, the reason why I put it in there is to spare a few cycles wasted on string comparison, so either I can shrug my shoulders, remove the check, waste the cycles and be happy or I can have a look whether gnulib can help us out here.