Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD

[Gerd Hoffmann <kraxel@redhat.com>]

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  Hi,

> > Another useful thing would be to not create the xen platform device in case
> > "-nodefaults" was specified on the command line (that switch turns off a bunch
> > of other devices present by default: vga, nic, cdrom, ...).
> 
> Currently looks 'xen-platform' itself can't be created, not those devices existed on that.

The error message looks more like libxl tries to hot-unplug the xen
platform device.

Attached patch (untested!) hooks up the xen platform device to the
default device code we have in qemu.  Two effects:

  (1) As mentioned above the device will not be created in case
      -nodefaults  is specified on the command line.
  (2) Autocreating the device is also turned off in case xen-platform
      is added manually via -device.

With the patch applied you should be able to move the xen-platform
device to some other place with a simple 'qemu -device
xen-platform,addr=$slot'.

cheers,
  Gerd


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>From 405349bf38fc05653bfb8c971c61796e981eee98 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 22 May 2014 08:34:28 +0200
Subject: [PATCH] xen: make xen-platform a default device

---
 hw/i386/pc_piix.c    | 2 +-
 include/hw/xen/xen.h | 1 +
 vl.c                 | 3 +++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index eaf3e61..f987d03 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -385,7 +385,7 @@ static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
     pc_init_pci(args);
 
     bus = pci_find_primary_bus();
-    if (bus != NULL) {
+    if (bus != NULL && default_xenplatform) {
         pci_create_simple(bus, -1, "xen-platform");
     }
 }
diff --git a/include/hw/xen/xen.h b/include/hw/xen/xen.h
index 85fda3d..b350413 100644
--- a/include/hw/xen/xen.h
+++ b/include/hw/xen/xen.h
@@ -20,6 +20,7 @@ enum xen_mode {
 
 extern uint32_t xen_domid;
 extern enum xen_mode xen_mode;
+extern int default_xenplatform;
 
 extern bool xen_allowed;
 
diff --git a/vl.c b/vl.c
index 709d8cd..673148e 100644
--- a/vl.c
+++ b/vl.c
@@ -226,6 +226,7 @@ static int default_floppy = 1;
 static int default_cdrom = 1;
 static int default_sdcard = 1;
 static int default_vga = 1;
+int default_xenplatform = 1;
 
 static struct {
     const char *driver;
@@ -247,6 +248,7 @@ static struct {
     { .driver = "isa-cirrus-vga",       .flag = &default_vga       },
     { .driver = "vmware-svga",          .flag = &default_vga       },
     { .driver = "qxl-vga",              .flag = &default_vga       },
+    { .driver = "xen-platform",         .flag = &default_xenplatform },
 };
 
 static QemuOptsList qemu_rtc_opts = {
@@ -4101,6 +4103,7 @@ int main(int argc, char **argv, char **envp)
         default_monitor = 0;
         default_net = 0;
         default_vga = 0;
+        default_xenplatform = 0;
     }
 
     if (is_daemonized()) {
-- 
1.8.3.1