[Qemu-devel] [PATCH 0/2] vl: Simplify vga interface configuration code

[Qemu-devel] [PATCH 0/2] vl: Simplify vga interface configuration code

[Eduardo Habkost]

Instead of duplicating class lookup and strstart() code for each
VGA interface type, use a table to implement select_vgahw().

This series needs the following patch to be applied first:

  From: Eduardo Habkost <ehabkost@redhat.com>
  Date: Wed, 11 Nov 2015 18:39:18 -0200
  Message-Id: <1447274358-2772-1-git-send-email-ehabkost@redhat.com>
  Subject: [PATCH] vl: Use exit(1) when requested VGA interface is unavailable

Eduardo Habkost (2):
  vl: Table-based select_vgahw()
  vl: Replace *_vga_available() functions with class_names field

 include/sysemu/sysemu.h |   1 +
 vl.c                    | 156 ++++++++++++++++++++++--------------------------
 2 files changed, 72 insertions(+), 85 deletions(-)

-- 
2.1.0

[Qemu-devel] [PATCH 1/2] vl: Table-based select_vgahw()

[Eduardo Habkost]

Instead of implementing separate check functions for each vga
interface type, add a table enumerating the possible VGA
interfaces.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 include/sysemu/sysemu.h |   1 +
 vl.c                    | 114 ++++++++++++++++++++++++++----------------------
 2 files changed, 63 insertions(+), 52 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index f992494..6406906 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -147,6 +147,7 @@ extern int autostart;
 typedef enum {
     VGA_NONE, VGA_STD, VGA_CIRRUS, VGA_VMWARE, VGA_XENFB, VGA_QXL,
     VGA_TCX, VGA_CG3, VGA_DEVICE, VGA_VIRTIO,
+    VGA_TYPE_MAX,
 } VGAInterfaceType;
 
 extern int vga_interface_type;
diff --git a/vl.c b/vl.c
index 7b81998..a5dd9a6 100644
--- a/vl.c
+++ b/vl.c
@@ -2001,63 +2001,73 @@ static bool virtio_vga_available(void)
     return object_class_by_name("virtio-vga");
 }
 
+typedef struct VGAInterfaceInfo {
+    const char *opt_name;    /* option name */
+    const char *name;        /* human-readable name */
+    bool (*available)(void);
+} VGAInterfaceInfo;
+
+static VGAInterfaceInfo vga_interfaces[VGA_TYPE_MAX] = {
+    [VGA_NONE] = {
+        .opt_name = "none",
+    },
+    [VGA_STD] = {
+        .opt_name = "std",
+        .name = "standard VGA",
+        .available = vga_available,
+    },
+    [VGA_CIRRUS] = {
+        .opt_name = "cirrus",
+        .name = "Cirrus VGA",
+        .available = cirrus_vga_available,
+    },
+    [VGA_VMWARE] = {
+        .opt_name = "vmware",
+        .name = "VMWare SVGA",
+        .available = vmware_vga_available,
+    },
+    [VGA_VIRTIO] = {
+        .opt_name = "virtio",
+        .name = "Virtio VGA",
+        .available = virtio_vga_available,
+    },
+    [VGA_QXL] = {
+        .opt_name = "qxl",
+        .name = "QXL VGA",
+        .available = qxl_vga_available,
+    },
+    [VGA_TCX] = {
+        .opt_name = "tcx",
+        .name = "TCX framebuffer",
+        .available = tcx_vga_available,
+    },
+    [VGA_CG3] = {
+        .opt_name = "cg3",
+        .name = "CG3 framebuffer",
+        .available = cg3_vga_available,
+    },
+    [VGA_XENFB] = {
+        .opt_name = "xenfb",
+    },
+};
+
 static void select_vgahw (const char *p)
 {
     const char *opts;
+    int t;
 
-    assert(vga_interface_type == VGA_NONE);
-    if (strstart(p, "std", &opts)) {
-        if (vga_available()) {
-            vga_interface_type = VGA_STD;
-        } else {
-            error_report("standard VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "cirrus", &opts)) {
-        if (cirrus_vga_available()) {
-            vga_interface_type = VGA_CIRRUS;
-        } else {
-            error_report("Cirrus VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "vmware", &opts)) {
-        if (vmware_vga_available()) {
-            vga_interface_type = VGA_VMWARE;
-        } else {
-            error_report("VMWare SVGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "virtio", &opts)) {
-        if (virtio_vga_available()) {
-            vga_interface_type = VGA_VIRTIO;
-        } else {
-            error_report("Virtio VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "xenfb", &opts)) {
-        vga_interface_type = VGA_XENFB;
-    } else if (strstart(p, "qxl", &opts)) {
-        if (qxl_vga_available()) {
-            vga_interface_type = VGA_QXL;
-        } else {
-            error_report("QXL VGA not available");
-            exit(1);
-        }
-    } else if (strstart(p, "tcx", &opts)) {
-        if (tcx_vga_available()) {
-            vga_interface_type = VGA_TCX;
-        } else {
-            error_report("TCX framebuffer not available");
-            exit(1);
-        }
-    } else if (strstart(p, "cg3", &opts)) {
-        if (cg3_vga_available()) {
-            vga_interface_type = VGA_CG3;
-        } else {
-            error_report("CG3 framebuffer not available");
-            exit(1);
+    for (t = 0; t < VGA_TYPE_MAX; t++) {
+        VGAInterfaceInfo *ti = &vga_interfaces[t];
+        if (ti->opt_name && strstart(p, ti->opt_name, &opts)) {
+            if (ti->available && !ti->available()) {
+                error_report("%s not available", ti->name);
+                exit(1);
+            }
+            vga_interface_type = t;
+            break;
         }
-    } else if (!strstart(p, "none", &opts)) {
+    }
+    if (t == VGA_TYPE_MAX) {
     invalid_vga:
         error_report("unknown vga type: %s", p);
         exit(1);
-- 
2.1.0

Re: [Qemu-devel] [PATCH 1/2] vl: Table-based select_vgahw()

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 2099 bytes --]

On 11/11/2015 02:27 PM, Eduardo Habkost wrote:
> Instead of implementing separate check functions for each vga
> interface type, add a table enumerating the possible VGA
> interfaces.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  include/sysemu/sysemu.h |   1 +
>  vl.c                    | 114 ++++++++++++++++++++++++++----------------------
>  2 files changed, 63 insertions(+), 52 deletions(-)
> 
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index f992494..6406906 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -147,6 +147,7 @@ extern int autostart;
>  typedef enum {
>      VGA_NONE, VGA_STD, VGA_CIRRUS, VGA_VMWARE, VGA_XENFB, VGA_QXL,
>      VGA_TCX, VGA_CG3, VGA_DEVICE, VGA_VIRTIO,
> +    VGA_TYPE_MAX,
>  } VGAInterfaceType;

Would it be worth exposing this enum in qapi someday? But doesn't affect
the correctness of this patch.

>  static void select_vgahw (const char *p)

Worth dropping the space before '(' while in the neighborhood?

>  {
>      const char *opts;
> +    int t;
>  
> -    assert(vga_interface_type == VGA_NONE);

Are you intentionally dropping the assert?  It protects us from
select_vgahw() being called more than once.

> -    } else if (strstart(p, "cg3", &opts)) {
> -        if (cg3_vga_available()) {
> -            vga_interface_type = VGA_CG3;
> -        } else {
> -            error_report("CG3 framebuffer not available");
> -            exit(1);
> +    for (t = 0; t < VGA_TYPE_MAX; t++) {
> +        VGAInterfaceInfo *ti = &vga_interfaces[t];
> +        if (ti->opt_name && strstart(p, ti->opt_name, &opts)) {
> +            if (ti->available && !ti->available()) {
> +                error_report("%s not available", ti->name);
> +                exit(1);
> +            }
> +            vga_interface_type = t;
> +            break;

Nice compression in code size.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH 1/2] vl: Table-based select_vgahw()

[Eduardo Habkost]

On Wed, Nov 11, 2015 at 03:05:07PM -0700, Eric Blake wrote:
> On 11/11/2015 02:27 PM, Eduardo Habkost wrote:
> > Instead of implementing separate check functions for each vga
> > interface type, add a table enumerating the possible VGA
> > interfaces.
> > 
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> >  include/sysemu/sysemu.h |   1 +
> >  vl.c                    | 114 ++++++++++++++++++++++++++----------------------
> >  2 files changed, 63 insertions(+), 52 deletions(-)
> > 
> > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> > index f992494..6406906 100644
> > --- a/include/sysemu/sysemu.h
> > +++ b/include/sysemu/sysemu.h
> > @@ -147,6 +147,7 @@ extern int autostart;
> >  typedef enum {
> >      VGA_NONE, VGA_STD, VGA_CIRRUS, VGA_VMWARE, VGA_XENFB, VGA_QXL,
> >      VGA_TCX, VGA_CG3, VGA_DEVICE, VGA_VIRTIO,
> > +    VGA_TYPE_MAX,
> >  } VGAInterfaceType;
> 
> Would it be worth exposing this enum in qapi someday? But doesn't affect
> the correctness of this patch.

I don't know. Maybe not, if we have any plans to configure this
using QOM classes somehow (like the CPU model stuff), not using
enums.

> 
> >  static void select_vgahw (const char *p)
> 
> Worth dropping the space before '(' while in the neighborhood?
> 
> >  {
> >      const char *opts;
> > +    int t;
> >  
> > -    assert(vga_interface_type == VGA_NONE);
> 
> Are you intentionally dropping the assert?  It protects us from
> select_vgahw() being called more than once.

That was not intentional. I will fix it in a new version. Thanks!

> 
> > -    } else if (strstart(p, "cg3", &opts)) {
> > -        if (cg3_vga_available()) {
> > -            vga_interface_type = VGA_CG3;
> > -        } else {
> > -            error_report("CG3 framebuffer not available");
> > -            exit(1);
> > +    for (t = 0; t < VGA_TYPE_MAX; t++) {
> > +        VGAInterfaceInfo *ti = &vga_interfaces[t];
> > +        if (ti->opt_name && strstart(p, ti->opt_name, &opts)) {
> > +            if (ti->available && !ti->available()) {
> > +                error_report("%s not available", ti->name);
> > +                exit(1);
> > +            }
> > +            vga_interface_type = t;
> > +            break;
> 
> Nice compression in code size.
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>

Thanks!

-- 
Eduardo

[Qemu-devel] [PATCH 2/2] vl: Replace *_vga_available() functions with class_names field

[Eduardo Habkost]

Instead of requiring a separate function for each VGA interface,
just enumerate the corresponding class names on struct
VGAInterfaceInfo.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 vl.c | 70 +++++++++++++++++++++++---------------------------------------------
 1 file changed, 23 insertions(+), 47 deletions(-)

diff --git a/vl.c b/vl.c
index a5dd9a6..c899adf 100644
--- a/vl.c
+++ b/vl.c
@@ -1965,46 +1965,12 @@ static const QEMUOption qemu_options[] = {
     { NULL },
 };
 
-static bool vga_available(void)
-{
-    return object_class_by_name("VGA") || object_class_by_name("isa-vga");
-}
-
-static bool cirrus_vga_available(void)
-{
-    return object_class_by_name("cirrus-vga")
-           || object_class_by_name("isa-cirrus-vga");
-}
-
-static bool vmware_vga_available(void)
-{
-    return object_class_by_name("vmware-svga");
-}
-
-static bool qxl_vga_available(void)
-{
-    return object_class_by_name("qxl-vga");
-}
-
-static bool tcx_vga_available(void)
-{
-    return object_class_by_name("SUNW,tcx");
-}
-
-static bool cg3_vga_available(void)
-{
-    return object_class_by_name("cgthree");
-}
-
-static bool virtio_vga_available(void)
-{
-    return object_class_by_name("virtio-vga");
-}
-
 typedef struct VGAInterfaceInfo {
     const char *opt_name;    /* option name */
     const char *name;        /* human-readable name */
-    bool (*available)(void);
+    /* Class names indicating that support is available.
+     * If no class is specified, the interface is always available */
+    const char *class_names[2];
 } VGAInterfaceInfo;
 
 static VGAInterfaceInfo vga_interfaces[VGA_TYPE_MAX] = {
@@ -2014,43 +1980,53 @@ static VGAInterfaceInfo vga_interfaces[VGA_TYPE_MAX] = {
     [VGA_STD] = {
         .opt_name = "std",
         .name = "standard VGA",
-        .available = vga_available,
+        .class_names = { "VGA", "isa-vga" },
     },
     [VGA_CIRRUS] = {
         .opt_name = "cirrus",
         .name = "Cirrus VGA",
-        .available = cirrus_vga_available,
+        .class_names = { "cirrus-vga", "isa-cirrus-vga" },
     },
     [VGA_VMWARE] = {
         .opt_name = "vmware",
         .name = "VMWare SVGA",
-        .available = vmware_vga_available,
+        .class_names = { "vmware-svga" },
     },
     [VGA_VIRTIO] = {
         .opt_name = "virtio",
         .name = "Virtio VGA",
-        .available = virtio_vga_available,
+        .class_names = { "virtio-vga" },
     },
     [VGA_QXL] = {
         .opt_name = "qxl",
         .name = "QXL VGA",
-        .available = qxl_vga_available,
+        .class_names = { "qxl-vga" },
     },
     [VGA_TCX] = {
         .opt_name = "tcx",
         .name = "TCX framebuffer",
-        .available = tcx_vga_available,
+        .class_names = { "SUNW,tcx" },
     },
     [VGA_CG3] = {
         .opt_name = "cg3",
         .name = "CG3 framebuffer",
-        .available = cg3_vga_available,
+        .class_names = { "cgthree" },
     },
     [VGA_XENFB] = {
         .opt_name = "xenfb",
     },
 };
 
+static bool vga_interface_available(VGAInterfaceType t)
+{
+    VGAInterfaceInfo *ti = &vga_interfaces[t];
+
+    assert(t < VGA_TYPE_MAX);
+    return !ti->class_names[0] ||
+           object_class_by_name(ti->class_names[0]) ||
+           object_class_by_name(ti->class_names[1]);
+}
+
 static void select_vgahw (const char *p)
 {
     const char *opts;
@@ -2059,7 +2035,7 @@ static void select_vgahw (const char *p)
     for (t = 0; t < VGA_TYPE_MAX; t++) {
         VGAInterfaceInfo *ti = &vga_interfaces[t];
         if (ti->opt_name && strstart(p, ti->opt_name, &opts)) {
-            if (ti->available && !ti->available()) {
+            if (!vga_interface_available(t)) {
                 error_report("%s not available", ti->name);
                 exit(1);
             }
@@ -4503,9 +4479,9 @@ int main(int argc, char **argv, char **envp)
     if (default_vga) {
         if (machine_class->default_display) {
             vga_model = machine_class->default_display;
-        } else if (cirrus_vga_available()) {
+        } else if (vga_interface_available(VGA_CIRRUS)) {
             vga_model = "cirrus";
-        } else if (vga_available()) {
+        } else if (vga_interface_available(VGA_STD)) {
             vga_model = "std";
         }
     }
-- 
2.1.0

Re: [Qemu-devel] [PATCH 2/2] vl: Replace *_vga_available() functions with class_names field

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1221 bytes --]

On 11/11/2015 02:27 PM, Eduardo Habkost wrote:
> Instead of requiring a separate function for each VGA interface,
> just enumerate the corresponding class names on struct
> VGAInterfaceInfo.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
>  vl.c | 70 +++++++++++++++++++++++---------------------------------------------
>  1 file changed, 23 insertions(+), 47 deletions(-)
> 

>      [VGA_CG3] = {
>          .opt_name = "cg3",
>          .name = "CG3 framebuffer",
> -        .available = cg3_vga_available,
> +        .class_names = { "cgthree" },
>      },
>      [VGA_XENFB] = {
>          .opt_name = "xenfb",
>      },
>  };
>  
> +static bool vga_interface_available(VGAInterfaceType t)
> +{
> +    VGAInterfaceInfo *ti = &vga_interfaces[t];
> +
> +    assert(t < VGA_TYPE_MAX);
> +    return !ti->class_names[0] ||
> +           object_class_by_name(ti->class_names[0]) ||
> +           object_class_by_name(ti->class_names[1]);

Does the correct thing when ti->class_names[1] is NULL (but I had to look).

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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