5.0 KiB
Haiku PCI Driver Development Under QEMU on Linux
Developing Haiku drivers for PCI and PCI Express cards is now a lot easier given advancements in IOMMU under Linux. You can effectively detach PCI cards from their host operating system and attach them to guest VM's resulting in true hardware emulation. In this guide we will be configuring a secondary graphics card to be attached to a Haiku virtual machine.
Warning: Any device attached to a VM will be unavailable to the host operating system. This means you cannot use your primary graphics card, network device, etc within a VM and the host operating system at the same time. In this example, we have two graphics cards installed in the Linux system.
IOMMU Setup
You will need to have IOMMU hardware support on your motherboard for this to function. Most modern AMD A3 socket chips and Intel i3/i5/i7 devices have IOMMU built in. If your board does indeed have IOMMU, you will likely need to enable IOMMU within the bios of your motherboard before proceeding.
Linux Setup
Now that you have an IOMMU enabled system, you will need to tell Linux to fully utilize IOMMU and reserve the PCI cards for IOMMU use.
Now, all we need to do is to reserve the PCI device. We want to make sure no host drivers attempt to attach to the PCI device in question.
First we need to find the PCIID for the device in question. We can find this through lcpci. Running lspci shows a bunch of devices. I've identified this device as my target:
$ lspci -nn | egrep "VGA|Audio"
28:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/580] [1002:67df] (rev c7)
28:00.1 Audio device [0403]: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 580] [1002:aaf0]
29:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Redwood XT GL [FirePro V4800] [1002:68c8]
29:00.1 Audio device [0403]: Advanced Micro Devices, Inc. [AMD/ATI] Redwood HDMI Audio [Radeon HD 5000 Series] [1002:aa60]
2b:00.3 Audio device [0403]: Advanced Micro Devices, Inc. [AMD] Device [1022:1457]
Now that we have our target PCI IDs (in this case, 1002:68c8,1002:aa60), we can bind this device to
the vfio-pci driver.
vfio-pci module
If your distro ships vfio-pci as a module, you will need to add the vfio drivers to the initial ramdisk to leverage them as early as possible in the boot process.
Below is an example on Fedora:
echo 'add_drivers+="vfio vfio_iommu_type1 vfio_pci vfio_virqfd"' > /etc/dracut.conf.d/vfio.conf
dracut -f --kver `uname -r`
vfio reservation
Now that the requirements are met, we can attach the target GPU to the vfio driver using the information we have collected so far.
Below, i've leveraged the PCI ID's collected above, and provided them to the vfio-pci driver via the kernel parameters at boot.
Be sure to replace with amd or intel depending on your system.
rd.driver.pre=vfio-pci vfio-pci.ids=1002:68c8,1002:aa60 <CPU>_iommu=on
YMMV: These steps differ a lot between distros
On my EFI Fedora 26 system, I appended the line above to my /etc/sysconfig/grub config under GRUB_CMDLINE_LINUX.
Then, regenerated my grub.cfg via grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
Attach GPU to VM
Now we reboot and cross our fingers.
If displays attached to the card are now black, then things are working as designed. If you see your desktop on the target GPU, the vfio driver didn't properly bind to your card and something was done incorrectly.
On my AMD Linux system, we can see that IOMMU is active and functional:
kallisti5@eris ~ $ dmesg | egrep "IOMMU|AMD-Vi"
[ 0.650138] AMD-Vi: IOMMU performance counters supported
[ 0.652201] AMD-Vi: Found IOMMU at 0000:00:00.2 cap 0x40
[ 0.652201] AMD-Vi: Extended features (0xf77ef22294ada):
[ 0.652204] AMD-Vi: Interrupt remapping enabled
[ 0.652204] AMD-Vi: virtual APIC enabled
[ 0.652312] AMD-Vi: Lazy IO/TLB flushing enabled
[ 0.653841] perf/amd_iommu: Detected AMD IOMMU #0 (2 banks, 4 counters/bank).
[ 4.114847] AMD IOMMUv2 driver by Joerg Roedel <jroedel@suse.de>
And checking for vfio we can see it successfully took over my graphics card:
kallisti5@eris ~ $ dmesg | grep vfio
[ 3.928695] vfio-pci 0000:29:00.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=none
[ 3.940222] vfio_pci: add [1002:68c8[ffff:ffff]] class 0x000000/00000000
[ 3.952302] vfio_pci: add [1002:aa60[ffff:ffff]] class 0x000000/00000000
[ 35.629861] vfio-pci 0000:29:00.0: enabling device (0000 -> 0003)
On every boot, the device will be available for attachment to VM's Now, we simply attach the device to a VM:
sudo qemu-system-x86_64 --enable-kvm -hda haiku-nightly-anyboot.image -m 2048 -device pci-assign,host=29:00.0
If you're doing this for a graphics card generally the qemu window will lock up at the bootsplash and the video will appear on the second window. Click the qemu window to control the Haiku machine.