66 lines
1.7 KiB
Plaintext
66 lines
1.7 KiB
Plaintext
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QEMU Standard VGA
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=================
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Exists in two variants, for isa and pci.
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command line switches:
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-vga std [ picks isa for -M isapc, otherwise pci ]
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-device VGA [ pci variant ]
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-device isa-vga [ isa variant ]
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PCI spec
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--------
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Applies to the pci variant only for obvious reasons.
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PCI ID: 1234:1111
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PCI Region 0:
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Framebuffer memory, 16 MB in size (by default).
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Size is tunable via vga_mem_mb property.
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PCI Region 1:
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Reserved (so we have the option to make the framebuffer bar 64bit).
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PCI Region 2:
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MMIO bar, 4096 bytes in size (qemu 1.3+)
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PCI ROM Region:
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Holds the vgabios (qemu 0.14+).
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IO ports used
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-------------
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03c0 - 03df : standard vga ports
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01ce : bochs vbe interface index port
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01cf : bochs vbe interface data port (x86 only)
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01d0 : bochs vbe interface data port
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Memory regions used
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-------------------
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0xe0000000 : Framebuffer memory, isa variant only.
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The pci variant used to mirror the framebuffer bar here, qemu 0.14+
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stops doing that (except when in -M pc-$old compat mode).
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MMIO area spec
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--------------
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Likewise applies to the pci variant only for obvious reasons.
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0000 - 03ff : reserved, for possible virtio extension.
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0400 - 041f : vga ioports (0x3c0 -> 0x3df), remapped 1:1.
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word access is supported, bytes are written
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in little endia order (aka index port first),
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so indexed registers can be updated with a
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single mmio write (and thus only one vmexit).
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0500 - 0515 : bochs dispi interface registers, mapped flat
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without index/data ports. Use (index << 1)
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as offset for (16bit) register access.
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