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.. SPDX-License-Identifier: GPL-2.0-or-later
Emulation of a graphics adapter
===============================
Currently QEMU's ``bochs-display`` is the only emulated GPU that U-Boot's
generic QEMU defconfigs support. It emulates a PCIe-connected graphics card
with VESA 2.0 VBE extensions.
The following parameters can be specified:
edid
controls whether EDID information is available. Allowable values are
``off`` and ``on``. The default is ``on``.
vgamem
specifies the display memory size. The default value is 16 MiB.
For UHD resolution 32 MiB is required.
The following configuration parameters are relevant:
CONFIG_VIDEO_BOCHS
enable support for the Bochs GPU.
CONFIG_VIDEO_BOCHS_SIZE_X
defines the display width.
CONFIG_VIDEO_BOCHS_SIZE_Y
defines the display height.
CONFIG_VIDEO_PCI_DEFAULT_FB_SIZE
sets the framebuffer size that QEMU can use for a device driver that is
enabled after relocation. This should be chosen as
.. code-block::
CONFIG_VIDEO_PCI_DEFAULT_FB_SIZE >=
4 * CONFIG_VIDEO_BOCHS_SIZE_X * CONFIG_VIDEO_BOCHS_SIZE_Y
Here is an example QEMU invocation for qemu-riscv64_smode_defconfig:
.. code-block:: bash
qemu-system-riscv64 \
-M virt \
-device bochs-display,vgamem=33554432 \
-serial mon:stdio \
-device qemu-xhci \
-device usb-kbd \
-kernel u-boot
``mon:stdio`` provides a serial console, ``qemu-xhci`` a USB root hub,
``usb-kbd`` a USB keyboard.
To start QEMU without GPU emulation, use parameter ``-nographic``, as shown in
the following example:
.. code-block:: bash
qemu-system-riscv64 \
-M virt \
-nographic \
-kernel u-boot
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