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
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.
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
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).
Likewise applies to the pci variant only for obvious reasons.
0000 - 03ff- edid data blob.
0400 - 041f- vga ioports (
0x3c0to0x3df), 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.
-
0xbebebebeindicates big endian. -0x1e1e1e1eindicates little endian.