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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
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QEMU Standard VGA | ||
================= | ||
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Exists in two variants, for isa and pci. | ||
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command line switches: | ||
-vga std [ picks isa for -M isapc, otherwise pci ] | ||
-device VGA [ pci variant ] | ||
-device isa-vga [ isa variant ] | ||
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PCI spec | ||
-------- | ||
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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: | ||
Framebuffer memory, 16 MB in size (by default). | ||
Size is tunable via vga_mem_mb property. | ||
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PCI Region 1: | ||
Reserved (so we have the option to make the framebuffer bar 64bit). | ||
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PCI Region 2: | ||
MMIO bar, 4096 bytes in size (qemu 1.3+) | ||
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PCI ROM Region: | ||
Holds the vgabios (qemu 0.14+). | ||
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IO ports used | ||
------------- | ||
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03c0 - 03df : standard vga ports | ||
01ce : bochs vbe interface index port | ||
01cf : bochs vbe interface data port | ||
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Memory regions used | ||
------------------- | ||
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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+ | ||
stops doing that (except when in -M pc-$old compat mode). | ||
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MMIO area spec | ||
-------------- | ||
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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. | ||
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. |
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