tools: add option to explicitly enable VirtFS in QEMU build

9pfs support has been a documented feature since Xen 4.9, but QEMU will
not be built with backend support unless VirtFS is enabled, which is
predicated on the libcap and libattr dev packages being installed. This is
not obvious to anyone intending to use 9pfs.

This patch adds an 'enable-9pfs' option to configure which, if specified,
will cause '--enable-virtfs' to be passed to QEMU's configure. This will
cause the dependency on libcap and libattr to be called out if the packages
are not in installed.

For completeness, specifying 'disable-9pfs' will cause '--disable-virtfs' to
be passed to QEMU's confgure and not specifying an option will keep the
previous behaviour of predicating VirtFS on whether the libcap and libattr
packages are installed.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Wei Liu <wei.liu2@citrix.com>

config/Tools.mk.in

@@ -62,6 +62,7 @@ SYSTEMD_CFLAGS      := @SYSTEMD_CFLAGS@
 SYSTEMD_LIBS        := @SYSTEMD_LIBS@
 XEN_SYSTEMD_DIR     := @SYSTEMD_DIR@
 XEN_SYSTEMD_MODULES_LOAD := @SYSTEMD_MODULES_LOAD@
+CONFIG_9PFS         := @ninepfs@
 
 LINUX_BACKEND_MODULES := @LINUX_BACKEND_MODULES@
 

tools/Makefile

@@ -232,6 +232,13 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find
 	else \
 		enable_trace_backend='' ; \
 	fi ; \
+	if [ "$(CONFIG_9PFS)" = "y" ]; then \
+		virtfs='--enable-virtfs' ; \
+	elif [ "$(CONFIG_9PFS)" = "n" ]; then \
+		virtfs='--disable-virtfs' ; \
+	else \
+		virtfs='' ; \
+	fi ; \
 	PKG_CONFIG_PATH=$(XEN_ROOT)/tools/pkg-config$${PKG_CONFIG_PATH:+:$${PKG_CONFIG_PATH}} \
 	$$source/configure --enable-xen --target-list=i386-softmmu \
 		$(QEMU_XEN_ENABLE_DEBUG) \
@@ -279,7 +286,8 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find
 		--python=$(PYTHON) \
 		$(CONFIG_QEMUU_EXTRA_ARGS) \
 		--cpu=$(IOEMU_CPU_ARCH) \
-		$(IOEMU_CONFIGURE_CROSS); \
+		$(IOEMU_CONFIGURE_CROSS) \
+		$$virtfs; \
 	$(MAKE) all
 
 subdir-install-qemu-xen-dir: subdir-all-qemu-xen-dir

tools/configure

@@ -624,6 +624,7 @@ ac_includes_default="\
 
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+ninepfs
 SYSTEMD_LIBS
 SYSTEMD_CFLAGS
 SYSTEMD_MODULES_LOAD
@@ -820,6 +821,7 @@ with_xenstored
 enable_systemd
 with_systemd
 with_systemd_modules_load
+enable_9pfs
 '
       ac_precious_vars='build_alias
 host_alias
@@ -1500,6 +1502,8 @@ Optional Features:
   --disable-ipxe          Enable in-tree IPXE, (DEFAULT is on if rombios is
                           enabled, otherwise off, see also --with-system-ipxe)
   --enable-systemd        Enable systemd support (default is DISABLED)
+  --enable-9pfs           Explicitly enable 9pfs support in QEMU build
+                          (default is to defer to QEMU configure default)
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -9799,6 +9803,18 @@ if test "x$systemd" = "xy"; then :
 
 fi
 
+# Check whether --enable-9pfs was given.
+if test "${enable_9pfs+set}" = set; then :
+  enableval=$enable_9pfs; if test "x$enable_9pfs" = "xyes"; then :
+  ninepfs=y
+else
+  ninepfs=n
+fi
+fi
+
+
+
+
 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure
@@ -11103,4 +11119,3 @@ if test -n "$ac_unrecognized_opts" && test "$enable_option_checking" != no; then
 $as_echo "$as_me: WARNING: unrecognized options: $ac_unrecognized_opts" >&2;}
 fi
 
-

tools/configure.ac

@@ -486,5 +486,12 @@ AS_IF([test "x$systemd" = "xy"], [
     ])
 ])
 
-AC_OUTPUT()
+AC_ARG_ENABLE([9pfs],
+    AS_HELP_STRING([--enable-9pfs],
+                   [Explicitly enable 9pfs support in QEMU build (default is to defer to QEMU configure default)]),
+    [AS_IF([test "x$enable_9pfs" = "xyes"], [ninepfs=y], [ninepfs=n])],[
+])
 
+AC_SUBST(ninepfs)
+
+AC_OUTPUT()