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Kernel: Use IO init method for Bochs emulated VGA adapter

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In short: QEMU supports both Memory-Mapped-IO and classic IO methods
for controlling the emulated VGA device. Bochs and VirtualBox only
support the classic IO method. An excellent write up on the history of
these interfaces can be found here:
https://www.kraxel.org/blog/2018/10/qemu-vga-emulation-and-bochs-display

The IO method was how things were done originally in SerenityOS. Commit
6a728e2d76 introduced the MMIO method for
all devices, breaking Bochs and VirtualBox compatibility. Later in
commit 6a9dc5562d the classic IO method
was restored for VirtualBox graphics adapters.

QEMU and Bochs use the same PCI VID/DID (0x1234/0x1111) for the emulated
VGA adapter. To distinguish betwen QEMU and Bochs we use the PCI
revision ID field (0=Bochs, 2=QEMU).
This commit is contained in:
Peter Ross 2022-02-22 21:06:36 +11:00 • committed by Idan Horowitz
parent 09262e3b77
commit 9d94c85b6a
1 changed files with 8 additions and 2 deletions
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10
Kernel/Graphics/Bochs/GraphicsAdapter.cpp
View file

@ -109,8 +109,14 @@ UNMAP_AFTER_INIT BochsGraphicsAdapter::BochsGraphicsAdapter(PCI::DeviceIdentifie
m_framebuffer_console = Graphics::ContiguousFramebufferConsole::initialize(PhysicalAddress(PCI::get_BAR0(pci_device_identifier.address()) & 0xfffffff0), 1024, 768, 1024 * sizeof(u32));
GraphicsManagement::the().set_console(*m_framebuffer_console);
// Note: If we use VirtualBox graphics adapter (which is based on Bochs one), we need to use IO ports
if (pci_device_identifier.hardware_id().vendor_id == 0x80ee && pci_device_identifier.hardware_id().device_id == 0xbeef)
auto vendor_id = pci_device_identifier.hardware_id().vendor_id;
auto device_id = pci_device_identifier.hardware_id().device_id;
auto revision_id = pci_device_identifier.revision_id();
auto is_bochs = vendor_id == PCI::VendorID::QEMUOld && device_id == 0x1111 && revision_id == 0;
auto is_virtualbox = vendor_id == PCI::VendorID::VirtualBox && device_id == 0xbeef;
if (is_bochs || is_virtualbox)
m_io_required = true;
if (pci_device_identifier.class_code().value() == 0x3 && pci_device_identifier.subclass_code().value() == 0x0)