1Haiku PCI Driver Development Under QEMU on Linux 2==================================================== 3 4> WARNING: This is an older guide under kernel 3.x using pci-stub 5> On newer kernels, you have to use vfio. 6 7Developing Haiku drivers for PCI and PCI Express cards is now a lot easier 8given advancements in IOMMU under Linux. You can effectively detach PCI cards 9from their host operating system and attach them to guest VM's resulting in 10true hardware emulation. In this guide we will be configuring a secondary 11graphics card to be attached to a Haiku virtual machine. 12 13**Warning**: Any device attached to a VM will be unavailable to the host operating 14system. This means you **cannot** use your primary graphics card, network device, 15etc within a VM and the host operating system at the same time. In this 16example, we have two graphics cards installed in the Linux system. 17 18IOMMU Setup 19----------------------- 20You will need to have IOMMU hardware support on your motherboard for this 21to function. Most modern AMD A3 socket chips and Intel i3/i5/i7 devices 22have IOMMU built in. If your board does indeed have IOMMU, you will likely 23need to enable IOMMU within the bios of your motherboard before proceeding. 24 25Linux Setup 26----------------------- 27Now that you have an IOMMU enabled system, you will need to tell Linux to 28fully utilize IOMMU. To do this, you will need to add a few kernel boot 29parameters. Depending on how your system is configured, there may be a few 30places to do this. Here are some example config files: 31 32 * `/etc/default/grub` (`GRUB_CMDLINE_LINUX_DEFAULT`) 33 * `/boot/grub/grub.cfg` 34 * `/boot/grub/menu.lst` 35 * `/boot/refind_linux.conf` 36 37Enabling OS support IOMMU for IOMMU involves adding one of the following 38kernel boot parameters: 39 40**AMD:** 41``` 42iommu=pt iommu=1 43``` 44**Intel:** 45``` 46intel_iommu=on 47``` 48 49Now, all we need to do is to reserve the PCI device. We want to make sure 50no host drivers attempt to attach to the PCI device in question. 51 52First we need to find the PCIID for the device in question. We can find 53this through lcpci. Running lspci shows a bunch of devices. I've identified 54this device as my target: 55 56``` 5707:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cedar [Radeon HD 5000] 58``` 59 60Now, to get the PCI ID, I run lspci again with the -n flag (lspci -n). We find 61the matching BUS ID and we get our PCI ID: 62 63``` 6407:00.0 0300: 1002:68f9 65``` 66 67Now that we have our target PCI ID (`1002:68f9`), we can bind this device to 68a special pci-stub driver. 69 70We will create two files for this graphics card: 71 72**`/lib/modprobe.d/pci-stub.conf`:** 73``` 74options pci-stub ids=1002:68f9 75``` 76 77**`/lib/modprobe.d/drm.conf`:** 78``` 79softdep drm pre: pci-stub 80``` 81 82The first line tells the pci-stub driver to bind to the device in question. 83The second line tells DRM (graphics driver stack) that it should make sure 84pci-stub loads before DRM (ensuring the device is stubbed and not loaded by 85DRM). 86 87Now we reboot and cross our fingers. 88 89On my AMD Linux system, we can see that IOMMU is active and functional: 90 91``` 92kallisti5@eris ~ $ dmesg | grep AMD-Vi 93[ 0.119400] [Firmware Bug]: AMD-Vi: IOAPIC[9] not in IVRS table 94[ 0.119406] [Firmware Bug]: AMD-Vi: IOAPIC[10] not in IVRS table 95[ 0.119409] [Firmware Bug]: AMD-Vi: No southbridge IOAPIC found 96[ 0.119412] AMD-Vi: Disabling interrupt remapping 97[ 1.823122] AMD-Vi: Found IOMMU at 0000:00:00.2 cap 0x40 98[ 1.823253] AMD-Vi: Initialized for Passthrough Mode 99``` 100 101And checking for pci-stub we can see it successfully took over my graphics card: 102``` 103kallisti5@eris ~ $ dmesg | grep pci-stub 104[ 3.685970] pci-stub: add 1002:68F9 sub=FFFFFFFF:FFFFFFFF cls=00000000/00000000 105[ 3.686002] pci-stub 0000:07:00.0: claimed by stub 106``` 107 108On every boot, the device will be available for attachment to VM's 109Now, we simply attach the device to a VM: 110 111``` 112sudo qemu-system-x86_64 --enable-kvm -hda haiku-nightly-anyboot.image -m 2048 -device pci-assign,host=07:00.0 113``` 114 115If you experience any problems, try looking at kvm messages: 116``` 117kallisti5@eris ~ $ dmesg | grep kvm 118``` 119 120If you're doing this for a graphics card generally the qemu window will 121lock up at the bootsplash and the video will appear on the second window. 122Click the qemu window to control the Haiku machine. 123 124If things go well you will see: 125``` 126[ 1966.132176] kvm: Nested Virtualization enabled 127[ 1966.132185] kvm: Nested Paging enabled 128[ 1972.212231] pci-stub 0000:07:00.0: kvm assign device 129[ 1974.186382] kvm: zapping shadow pages for mmio generation wraparound 130``` 131