Hardware

This page documents how Dennix configures hardware devices and which features are used under which circumstances.

CPU

• The CPU must support SSE
• If the CPU supports the rdrand instruction then the rdrand instruction will be used to generate entropy

Interrupt controllers

• If the ACPI tables contain a valid MADT then
  • the APIC is used
  • any I/O APICs listed in the MADT are used
  • PCI interrupt lines are not supported in this case
• If no I/O APICs are used then
  • Two 8259 PICs are assumed to be present and are used

Timers

• If the ACPI table contain a valid HPET table then
  • If timer 0 of the HPET does not support periodic mode then the HPET is unsupported
  • If the HPET supports FSB then the HPET is configured using FSB
  • Otherwise if the HPET support the Legacy Replacement Routing then the HPET is configured using the Legacy Replacement Routing
  • Otherwise if the HPET supports routing to APIC IRQ16 or higher then the HPET is configured to use the lowest supported IRQ equal to or higher than IRQ16
  • Otherwise the HPET is unsupported
• If the HPET is not used then
  • The PIT is assumed to be present and is used

ATA

• If the ATA controllers does not support bus mastering then it is unsupported
• Interrupt routing:
  • If the ATA channels default to ISA compatibility mode then they operate in ISA compatibility mode
  • Otherwise if the APIC is not used then the ATA channels operate in PCI native mode
  • Otherwise if the ATA controller supports MSI then the ATA channels operate in PCI native mode using MSI
  • Otherwise if both ATA channels support switching to ISA compatibility mode then the ATA channels operate in ISA compatibility mode
  • Otherwise the ATA controller is unsupported
• Reads and writes are always performed as DMA transfers

AHCI

• AHCI controllers that do not support 64-bit addressing are unsupported
• AHCI devices that do not support LBA48 are unsupported

BGA

• When a BGA device is available it is used to allow changing the display resolution