qemu: retain default trace backend if 'ust' is not enabled

The qemu build system enables the 'log' trace backend by default, if no
explicit choice was made with '--enable-trace-backend=CHOICE'.

However, the qemu recipe uses the following PACKAGECONFIG line:
    PACKAGECONFIG[ust] = "--enable-trace-backend=ust,--enable-trace-backend=nop,lttng-ust,"

which means that the 'nop' trace backend will be explicitly selected if the
'ust' feature is not enabled. The 'nop' backend removes almost all trace
points at compile time, and thus basically means 'disable tracing'.

To retain the default trace backend if 'ust' is not enabled, the above
PACKAGECONFIG line should either explicitly fall back to the 'log' backend,
or not provide any value for the 'disabled' case. This commit chooses the
latter to not make any assumption about the upstream default.

(From OE-Core rev: c31396a30dcf17ab23ff4dd5943eef5fba20cba6)

Signed-off-by: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Kai Kang <kai.kang@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

diff --git a/meta/recipes-devtools/qemu/qemu.inc b/meta/recipes-devtools/qemu/qemu.inc
index cae33459e6108621e940b7db49e3d2cacabdaaee..81fc3047699e5f043d6cfda7b8bb02b0a3c8ba1e 100644 (file)
--- a/meta/recipes-devtools/qemu/qemu.inc
+++ b/meta/recipes-devtools/qemu/qemu.inc
@@ -301,7 +301,7 @@ PACKAGECONFIG[libxml2] = "--enable-libxml2,--disable-libxml2,libxml2"
 PACKAGECONFIG[attr] = "--enable-attr,--disable-attr,attr,"
 PACKAGECONFIG[rbd] = "--enable-rbd,--disable-rbd,ceph,ceph"
 PACKAGECONFIG[vhost] = "--enable-vhost-net,--disable-vhost-net,,"
-PACKAGECONFIG[ust] = "--enable-trace-backend=ust,--enable-trace-backend=nop,lttng-ust,"
+PACKAGECONFIG[ust] = "--enable-trace-backend=ust,,lttng-ust,"
 PACKAGECONFIG[pie] = "--enable-pie,--disable-pie,,"
 PACKAGECONFIG[seccomp] = "--enable-seccomp,--disable-seccomp,libseccomp"
 # libnfs is currently provided by meta-kodi