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QEMU Standard VGA
=================
Exists in two variants, for isa and pci.
command line switches:
``-vga std``
picks isa for -M isapc, otherwise pci
``-device VGA``
pci variant
``-device isa-vga``
isa variant
``-device secondary-vga``
legacy-free pci variant
PCI spec
--------
Applies to the pci variant only for obvious reasons.
PCI ID
``1234:1111``
PCI Region 0
Framebuffer memory, 16 MB in size (by default).
Size is tunable via vga_mem_mb property.
PCI Region 1
Reserved (so we have the option to make the framebuffer bar 64bit).
PCI Region 2
MMIO bar, 4096 bytes in size (QEMU 1.3+)
PCI ROM Region
Holds the vgabios (QEMU 0.14+).
The legacy-free variant has no ROM and has ``PCI_CLASS_DISPLAY_OTHER``
instead of ``PCI_CLASS_DISPLAY_VGA``.
IO ports used
-------------
Doesn't apply to the legacy-free pci variant, use the MMIO bar instead.
``03c0 - 03df``
standard vga ports
``01ce``
bochs vbe interface index port
``01cf``
bochs vbe interface data port (x86 only)
``01d0``
bochs vbe interface data port
Memory regions used
-------------------
``0xe0000000``
Framebuffer memory, isa variant only.
The pci variant used to mirror the framebuffer bar here, QEMU 0.14+
stops doing that (except when in ``-M pc-$old`` compat mode).
MMIO area spec
--------------
Likewise applies to the pci variant only for obvious reasons.
``0000 - 03ff``
edid data blob.
``0400 - 041f``
vga ioports (``0x3c0`` to ``0x3df``), remapped 1:1. Word access
is supported, bytes are written in little endian order (aka index
port first), so indexed registers can be updated with a single
mmio write (and thus only one vmexit).
``0500 - 0515``
bochs dispi interface registers, mapped flat without index/data ports.
Use ``(index << 1)`` as offset for (16bit) register access.
``0600 - 0607``
QEMU extended registers. QEMU 2.2+ only.
The pci revision is 2 (or greater) when these registers are present.
The registers are 32bit.
``0600``
QEMU extended register region size, in bytes.
``0604``
framebuffer endianness register.
- ``0xbebebebe`` indicates big endian.
- ``0x1e1e1e1e`` indicates little endian.
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