Warn user if the vga flag is passed but no vga device is created

A global boolean variable "vga_interface_created"(declared in softmmu/globals.c)
has been used to track the creation of vga interface. If the vga flag is passed
in the command line "default_vga"(declared in softmmu/vl.c) variable is set to 0.
To warn user, the condition checks if vga_interface_created is false
and default_vga is equal to 0. If "-vga none" is passed, this patch will not warn the
user regarding the creation of VGA device.

The warning "A -vga option was passed but this
machine type does not use that option; no VGA device has been created"
is logged if vga flag is passed but no vga device is created.

This patch has been tested for x86_64, i386, sparc, sparc64 and arm boards.

Signed-off-by: Gautam Agrawal <gautamnagrawal@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/581
Message-Id: <20220501122505.29202-1-gautamnagrawal@gmail.com>
[thuth: Fix wrong warning with "-device" in some cases as reported by Paolo]
Signed-off-by: Thomas Huth <thuth@redhat.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/hw/sparc/sun4m.c b/hw/sparc/sun4m.c
index fccaed1eb4..b693eea0e0 100644
--- a/hw/sparc/sun4m.c
+++ b/hw/sparc/sun4m.c
@@ -920,6 +920,7 @@ static void sun4m_hw_init(MachineState *machine)
             /* sbus irq 5 */
             cg3_init(hwdef->tcx_base, slavio_irq[11], 0x00100000,
                      graphic_width, graphic_height, graphic_depth);
+            vga_interface_created = true;
         } else {
             /* If no display specified, default to TCX */
             if (graphic_depth != 8 && graphic_depth != 24) {
@@ -935,6 +936,7 @@ static void sun4m_hw_init(MachineState *machine)
 
             tcx_init(hwdef->tcx_base, slavio_irq[11], 0x00100000,
                      graphic_width, graphic_height, graphic_depth);
+            vga_interface_created = true;
         }
     }