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Kvmtool is a virtual machine manager that enables hosting
KVM guests. Kvmtool emulates certain devices like serial
port, RTC, etc. essentially providing a virtual platform.
This patch adds support for kvmtool virtual platform.
Following is a brief description of the firmware
implementation choices:
- Serial Port: 16550 UART
On some platforms the 16550 UART is interfaced using
PCI. Therefore, the 16550 Serial port library is
dependent on the PCI library. The 16550 UART driver
checks the Device ID represented using the PCD
gEfiMdeModulePkgTokenSpaceGuid.PcdSerialPciDeviceInfo
to determine if the UART is behind PCI.
If the Device ID is 0xFF then the serial 16550 UART
is not behind PCI.
On Kvmtool the Serial 16550 UART is not behind PCI,
and therefore a combination of BasePciLibPciExpress
and BasePciExpressLib is used to satisfy the PCI
library dependency.
The PcdSerialPciDeviceInfo is also set to 0xFF to
indicate that the Serial 16550 UART is not behind
PCI. The PCD PcdSerialUseMmio is also set to TRUE
to indicate MMIO accesses are required for the
UART registers.
Additionally two instances of PlatformHookLibs are
provided EarlyFdt16550SerialPortHookLib and
Fdt16550SerialPortHookLib to patch the
PcdSerialRegisterBase so that BaseSerialPortLib16550
and retrieve the base address of the 16550 UART.
- Dependency order for Flash
FaultTolerantWriteDxe makes use of PCDs (e.g.
PcdFlashNvStorageFtwSpareBase64 etc.), which in
case of kvmtool will be evaluated based on the CFI
flash base address read from the DT. These variables
are populated in the NorFlashPlatformLib loaded by
ArmVeNorFlashDxe.
This results in a dependency issue with
FaultTolerantWriteDxe. To resolve this make the
NorFlashPlatformLib as a library dependency for
FaultTolerantWriteDxe.
- RTC Controller
A separate patch updates the MC146818 RTC controller
driver to support MMIO accesses.
A KvmtoolRtcFdtClientLib has been introduced to
extract the base addresses of the RTC controller
from the platform device tree and map the RTC
register space as Runtime Memory.
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
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