Re: [Xen-devel] [Xen-users] XEN/arm XENFB support

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-12-16 at 08:45 +0000, Lars Kurth wrote:

> On Mon, Dec 16, 2013 at 8:16 AM, peter <peter@xxxxxxxxxx> wrote:
>         I'm currently playing with XEN/arm on my Allwinner A20 (cubieboard2)
>         I would like to get the XENFB driver working on domU.
>         But currently in xen/arm there's no support for VFB, atleast qemu is 
> not
>         supported.
>         But this video http://www.youtube.com/watch?v=po1IeElg8tg and this one
>         http://www.youtube.com/watch?v=Km6gBnIqaWo is showing a working 
> framebuffer.
>         So there are people which got a framebuffer working on domU.
>         But still i couldn't find anything on the internet how to do this.
>         Is there anyone with experience with VFB on xen/arm ?

I'm not sure what the first link used but the second was using a form of
hybrid GPU passthrough/paravirtualisation for which the code has not
been reeleased and AFAIK has nothing to do with VFB.

I've not tried VFB on ARM yet (busy with other things) but I suspect
that if you were to build upstream qemu on ARM with Xen support enabled
then it would just work. I would recommend giving that a go -- please
let us know how you get on.

Below is a patch which I wrote ages ago that I have just rebased onto
current xen staging *without retesting*. It is supposed to DTWT and
enable the qemu build for ARM (as well as providing a mechanism to start
the correct dom0 qemu, which you don't need for vfb).

As I say I haven't tested, or even built, and in particular I never
tried PVFB with it even what I wrote it, so YMMV.

Ian.


commit 7b5d54c9a5d09c4138bec905c9accea34173ba77
Author: Ian Campbell <ian.campbell@xxxxxxxxxx>
Date:   Wed May 15 16:34:55 2013 +0100

    tools: build and launch correct qemu for architecture
    
    xl now provides a launch-dom0-qemu command which avoids the need to have the
    initscripts be aware of the specific qermu binary name, which differs by
    architecture and which also may have been specified by the user via the
    --with-system-qemu=PATH option to configure.
    
    Perhaps this should be a separate binary hidden in libexec?
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff --git a/config/arm32.mk b/config/arm32.mk
index aa79d22..f3599a3 100644
--- a/config/arm32.mk
+++ b/config/arm32.mk
@@ -3,6 +3,8 @@ CONFIG_ARM_32 := y
 CONFIG_ARM_$(XEN_OS) := y
 
 CONFIG_XEN_INSTALL_SUFFIX :=
+CONFIG_QEMU_ARCH := arm
+CONFIG_QEMU_TARGET := arm-softmmu
 
 # -march= -mcpu=
 
diff --git a/config/arm64.mk b/config/arm64.mk
index 15b57a4..4ff15e0 100644
--- a/config/arm64.mk
+++ b/config/arm64.mk
@@ -3,6 +3,8 @@ CONFIG_ARM_64 := y
 CONFIG_ARM_$(XEN_OS) := y
 
 CONFIG_XEN_INSTALL_SUFFIX :=
+CONFIG_QEMU_ARCH := aarch64
+CONFIG_QEMU_TARGET := arm-softmmu
 
 CFLAGS += #-marm -march= -mcpu= etc
 
diff --git a/config/x86_32.mk b/config/x86_32.mk
index 7f76b25..da3111d 100644
--- a/config/x86_32.mk
+++ b/config/x86_32.mk
@@ -2,6 +2,9 @@ CONFIG_X86 := y
 CONFIG_X86_32 := y
 CONFIG_X86_$(XEN_OS) := y
 
+CONFIG_QEMU_ARCH := i386
+CONFIG_QEMU_TARGET := i386-softmmu
+
 CONFIG_HVM := y
 CONFIG_MIGRATE := y
 CONFIG_XCUTILS := y
diff --git a/config/x86_64.mk b/config/x86_64.mk
index 11104bd..f59e36d 100644
--- a/config/x86_64.mk
+++ b/config/x86_64.mk
@@ -2,6 +2,9 @@ CONFIG_X86 := y
 CONFIG_X86_64 := y
 CONFIG_X86_$(XEN_OS) := y
 
+CONFIG_QEMU_ARCH := x86_64
+CONFIG_QEMU_ARCH := i386-softmmu
+
 CONFIG_COMPAT := y
 CONFIG_HVM := y
 CONFIG_MIGRATE := y
diff --git a/tools/Makefile b/tools/Makefile
index 00c69ee..250b931 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -107,7 +107,7 @@ distclean: subdirs-distclean
                config.cache autom4te.cache
 
 ifneq ($(XEN_COMPILE_ARCH),$(XEN_TARGET_ARCH))
-IOEMU_CONFIGURE_CROSS ?= --cpu=$(XEN_TARGET_ARCH) \
+IOEMU_CONFIGURE_CROSS ?= --cpu=$(CONFIG_QEMU_ARCH) \
                         --cross-prefix=$(CROSS_COMPILE) \
                         --interp-prefix=$(CROSS_SYS_ROOT)
 endif
@@ -186,8 +186,7 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find
                source=.; \
        fi; \
        cd qemu-xen-dir; \
-       $$source/configure --enable-xen --target-list=i386-softmmu \
-               $(QEMU_XEN_ENABLE_DEBUG) \
+       $$source/configure --enable-xen --target-list=$(CONFIG_QEMU_TARGET) \
                --prefix=$(PREFIX) \
                --source-path=$$source \
                --extra-cflags="-I$(XEN_ROOT)/tools/include \
diff --git a/tools/hotplug/Linux/init.d/xencommons 
b/tools/hotplug/Linux/init.d/xencommons
index 4ebd636..f568085 100644
--- a/tools/hotplug/Linux/init.d/xencommons
+++ b/tools/hotplug/Linux/init.d/xencommons
@@ -116,11 +116,7 @@ do_start () {
        echo Starting xenconsoled...
        test -z "$XENCONSOLED_TRACE" || XENCONSOLED_ARGS=" 
--log=$XENCONSOLED_TRACE"
        ${SBINDIR}/xenconsoled --pid-file=$XENCONSOLED_PIDFILE $XENCONSOLED_ARGS
-       echo Starting QEMU as disk backend for dom0
-       test -z "$QEMU_XEN" && QEMU_XEN="${LIBEXEC}/qemu-system-i386"
-       $QEMU_XEN -xen-domid 0 -xen-attach -name dom0 -nographic -M xenpv 
-daemonize \
-               -monitor /dev/null -serial /dev/null -parallel /dev/null \
-               -pidfile $QEMU_PIDFILE
+       xl launch-dom0-qemu $QEMU_XEN
 }
 do_stop () {
         echo Stopping xenconsoled
diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
index d8495bb..d8b6a5c 100644
--- a/tools/libxl/Makefile
+++ b/tools/libxl/Makefile
@@ -27,6 +27,7 @@ CFLAGS_LIBXL += $(CFLAGS_libxenguest)
 CFLAGS_LIBXL += $(CFLAGS_libxenstore)
 CFLAGS_LIBXL += $(CFLAGS_libblktapctl) 
 CFLAGS_LIBXL += -Wshadow
+CFLAGS_LIBXL += -DCONFIG_QEMU_ARCH=\"$(CONFIG_QEMU_ARCH)\"
 
 LIBXL_LIBS-$(CONFIG_ARM) += -lfdt
 
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 12d6c31..0287a35 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -605,6 +605,9 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
                     xentoollog_logger *lg);
 int libxl_ctx_free(libxl_ctx *ctx /* 0 is OK */);
 
+/* exec's device model for dom0 and does not return. */
+void libxl_launch_dom0_qemu(libxl_ctx *ctx, const char *qemu_path, const char 
*pidfile);
+
 /* domain related functions */
 
 int libxl_domain_create_new(libxl_ctx *ctx, libxl_domain_config *d_config,
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index f6f7bbd..f0b13a9 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -38,7 +38,7 @@ static const char *qemu_xen_path(libxl__gc *gc)
 #ifdef QEMU_XEN_PATH
     return QEMU_XEN_PATH;
 #else
-    return libxl__abs_path(gc, "qemu-system-i386", libxl__libexec_path());
+    return libxl__abs_path(gc, "qemu-system-" CONFIG_QEMU_ARCH, 
libxl__libexec_path());
 #endif
 }
 
@@ -1560,6 +1560,37 @@ out:
     return ret;
 }
 
+void libxl_launch_dom0_qemu(libxl_ctx *ctx, const char *qemu_path, const char 
*pidfile)
+{
+    GC_INIT(ctx);
+
+    flexarray_t *dm_args = flexarray_make(gc, 16, 1);
+
+    if (qemu_path == NULL)
+        qemu_path = qemu_xen_path(gc);
+
+    flexarray_vappend(dm_args,
+                      "-xen-domid", "0",
+                      "-xen-attach",
+                      "-name", "dom0",
+                      "-nographic",
+                      "-M" "xenpv",
+                      "-daemonize",
+                      "-monitor", "/dev/null",
+                      "-serial", "/dev/null",
+                      "-parallel", "/dev/null",
+                      NULL);
+    if (pidfile)
+        flexarray_append_pair(dm_args, "-pidfile", libxl__strdup(gc, pidfile));
+
+    libxl__exec(gc, -1, -1, -1,
+                qemu_path, (char **)flexarray_contents(dm_args), NULL);
+
+    /* Shouldn't return */
+    LOG(CRITICAL, "Failed to exec dom0 device model");
+    GC_FREE;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/xl.h b/tools/libxl/xl.h
index c876a33..1d7602c 100644
--- a/tools/libxl/xl.h
+++ b/tools/libxl/xl.h
@@ -106,6 +106,7 @@ int main_setenforce(int argc, char **argv);
 int main_loadpolicy(int argc, char **argv);
 int main_remus(int argc, char **argv);
 int main_devd(int argc, char **argv);
+int main_launch_dom0_qemu(int argc, char **argv);
 
 void help(const char *command);
 
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index bd26bcc..108dfac 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -7313,6 +7313,31 @@ out:
     return ret;
 }
 
+int main_launch_dom0_qemu(int argc, char **argv)
+{
+    int opt;
+    const char *qemu = NULL;
+    const char *pidfile = NULL;
+
+    SWITCH_FOREACH_OPT(opt, "p:", NULL, "launch-dom-qemu", 0) {
+    case 'p':
+        pidfile = optarg;
+        break;
+        /* No options */
+    }
+    if (optind < argc)
+        qemu = argv[optind];
+
+    fprintf(stderr, "argc %d\n", argc);
+    fprintf(stderr, "qemu = %s", qemu ? : "<default>");
+
+    fprintf(stdout, "Starting QEMU as disk backend for dom0");
+
+    libxl_launch_dom0_qemu(ctx, qemu, pidfile);
+
+    return 0;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/xl_cmdtable.c b/tools/libxl/xl_cmdtable.c
index ebe0220..ab4d56c 100644
--- a/tools/libxl/xl_cmdtable.c
+++ b/tools/libxl/xl_cmdtable.c
@@ -494,6 +494,12 @@ struct cmd_spec cmd_table[] = {
       "[options]",
       "-F                      Run in the foreground",
     },
+    { "launch-dom0-qemu",
+      &main_launch_dom0_qemu, 0, 1,
+      "Start qemu process to service dom0 disk backends",
+      "[options] [QEMU_PATH]",
+      "-p PIDFILE              Write a PIDFILE\n",
+    },
 };
 
 int cmdtable_len = sizeof(cmd_table)/sizeof(struct cmd_spec);



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