:FreeBSD operating system compatibility

Support in the Alibaba Cloud console

The following examples illustrate the support differences for FreeBSD in the Alibaba Cloud console.

Support for FreeBSD 11/12

FreeBSD 11 and 12 require kernel patches to run on ECS instances of fifth-generation or later instance families. Without these patches, the operating system cannot start. The public images for FreeBSD provided by Alibaba Cloud include these patches and support these instance families. You can check the instance family generation by calling the DescribeInstanceTypeFamilies API operation and checking the Generation parameter.

The operating system may fail to start in the following scenarios. To prevent or resolve this issue, you can apply a patch to the FreeBSD kernel source code and compile the kernel.

• If you use a custom image or a FreeBSD image not provided by Alibaba Cloud to create an ECS instance, the instance may fail to start if it belongs to a fifth-generation or later instance family.

• If you use a public image of FreeBSD to create an ECS instance and then update the kernel by using a command such as freebsd-update, the instance may fail to start if it belongs to a fifth-generation or later instance family.

  Note

  You can use freebsd-update to upgrade to a FreeBSD 13 release. For details, see Upgrade FreeBSD across major releases.

This example shows how to patch and compile the kernel using the FreeBSD 12.4 source code.

1. Download and decompress the FreeBSD kernel source code.

   wget https://mirrors.aliyun.com/freebsd/releases/amd64/12.4-RELEASE/src.txz -O /src.txz
   cd /
   tar -zxvf /src.txz

2. Download the patch.

   This example applies 0001-virtio.patch to the virtio driver.

   cd /usr/src/sys/dev/virtio/
   wget https://ecs-image-tools.oss-cn-hangzhou.aliyuncs.com/0001-virtio.patch
   patch -p4 < 0001-virtio.patch

3. Copy the kernel configuration file, and then compile and install the kernel.

   The make -j<N> command specifies the number of parallel compilation jobs. The value of N depends on your vCPU count. For example, on an instance with 1 vCPU, we recommend setting the value to -j2 for a vCPU-to-job ratio of 1:2.

   cd /usr/src/
   cp ./sys/amd64/conf/GENERIC .
   make -j2 buildworld KERNCONF=GENERIC
   make -j2 buildkernel KERNCONF=GENERIC
   make -j2 installkernel KERNCONF=GENERIC

4. After the compilation is complete, delete the source code.

   rm -rf /usr/src/*
   rm -rf /usr/src/.*

Support for FreeBSD 13 and later

FreeBSD 13 and later versions already include the kernel patches required to run on fifth-generation and later ECS instance families. The relevant patches are:

• virtio_pci_legacy: Allow memory space for configuration

• virtio_pci_legacy: Use the table BAR and PBA BAR from MSI-X cap

However, you must add the kern.maxphys=65536 kernel parameter to ensure the system runs correctly. Run the following command to set this parameter:

echo "kern.maxphys=65536" >>/boot/loader.conf

The official Alibaba Cloud public image for FreeBSD 13 uses kernel version 13.0-Release-p8. This image includes both patches and the required kernel parameter, making it ready to use.

Upgrade FreeBSD across major releases

This example shows how to upgrade FreeBSD from version 12.3 to 13.1.

1. Run the upgrade command.

   freebsd-update upgrade -r 13.1-RELEASE

Expected output:

2. Follow the prompts to run the installation command.

   /usr/sbin/freebsd-update install

Expected output:

3. Run the following command to configure loader.conf to ensure the new system runs correctly.

   echo "kern.maxphys=65536" >>/boot/loader.conf

4. Run the following command to restart the instance.

   Warning

   Restarting the instance causes it to stop, which may interrupt your services. We recommend that you perform this operation during off-peak hours.

   reboot

5. Run the following command to check the version.

   uname -r

If the upgrade was successful, the output shows the new version number.

References

For more information about FreeBSD, see the FreeBSD official documentation.