[qemu.git] / docs / specs / standard-vga.txt


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 -> 0x3df), remapped 1:1.
              word access is supported, bytes are written
              in little endia 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.
Commit	Line	Data
cc228248 GH	1
	2	QEMU Standard VGA
	3	=================
	4
	5	Exists in two variants, for isa and pci.
	6
	7	command line switches:
63e3e24d GH	8	-vga std [ picks isa for -M isapc, otherwise pci ]
	9	-device VGA [ pci variant ]
	10	-device isa-vga [ isa variant ]
	11	-device secondary-vga [ legacy-free pci variant ]
cc228248 GH	12
	13
	14	PCI spec
	15	--------
	16
	17	Applies to the pci variant only for obvious reasons.
	18
	19	PCI ID: 1234:1111
	20
	21	PCI Region 0:
	22	Framebuffer memory, 16 MB in size (by default).
	23	Size is tunable via vga_mem_mb property.
	24
	25	PCI Region 1:
	26	Reserved (so we have the option to make the framebuffer bar 64bit).
	27
	28	PCI Region 2:
	29	MMIO bar, 4096 bytes in size (qemu 1.3+)
	30
	31	PCI ROM Region:
	32	Holds the vgabios (qemu 0.14+).
	33
	34
63e3e24d GH	35	The legacy-free variant has no ROM and has PCI_CLASS_DISPLAY_OTHER
	36	instead of PCI_CLASS_DISPLAY_VGA.
	37
	38
cc228248 GH	39	IO ports used
	40	-------------
	41
63e3e24d GH	42	Doesn't apply to the legacy-free pci variant, use the MMIO bar instead.
63e3e24d GH	43
cc228248 GH	44	03c0 - 03df : standard vga ports
cc228248 GH	45	01ce : bochs vbe interface index port
df9ffb72 GH	46	01cf : bochs vbe interface data port (x86 only)
df9ffb72 GH	47	01d0 : bochs vbe interface data port
cc228248 GH	48
	49
	50	Memory regions used
	51	-------------------
	52
	53	0xe0000000 : Framebuffer memory, isa variant only.
	54
	55	The pci variant used to mirror the framebuffer bar here, qemu 0.14+
	56	stops doing that (except when in -M pc-$old compat mode).
	57
	58
	59	MMIO area spec
	60	--------------
	61
	62	Likewise applies to the pci variant only for obvious reasons.
	63
d46b40fc	64	0000 - 03ff : edid data blob.
cc228248 GH	65	0400 - 041f : vga ioports (0x3c0 -> 0x3df), remapped 1:1.
	66	word access is supported, bytes are written
	67	in little endia order (aka index port first),
	68	so indexed registers can be updated with a
	69	single mmio write (and thus only one vmexit).
	70	0500 - 0515 : bochs dispi interface registers, mapped flat
	71	without index/data ports. Use (index << 1)
	72	as offset for (16bit) register access.
b5682aa4 GH	73
	74	0600 - 0607 : qemu extended registers. qemu 2.2+ only.
	75	The pci revision is 2 (or greater) when
	76	these registers are present. The registers
	77	are 32bit.
	78	0600 : qemu extended register region size, in bytes.
	79	0604 : framebuffer endianness register.
	80	- 0xbebebebe indicates big endian.
	81	- 0x1e1e1e1e indicates little endian.