BSP¶
In addition to containers, Pantavisor is in charge of the life-cycle of the Linux kernel, modules and firmware. To allow upgrading all this plus Pantavisor itself, all these binaries have been included under the BSP denomination in the state JSON.
Pantavisor¶
The Pantavisor binary and dependency tree are part of the revision BSP in the state JSON.
Addons¶
Additional files can be added to Pantavisor initrd rootfs without having to do it during compile time.
It is important to remark that the binary file has to be under cpio.xz4 compression. That is, cpio.xz with 4 Byte alignment. You can take a look at how we do the cpio.xz4 compression at this example. For the rest of gdbserver installation and use, go here.
Linux Kernel¶
The Linux Kernel, modules and firmware are also part of the revision BSP of the state JSON.
Managed Drivers¶
Pantavisor offers a declarative way to define a list of drivers at BSP level, each driver being just a set of Kernel modules. Parameters for Kernel loading are supported too by mapping drivers to device or user metadata.
The modules that are part of a driver will only be loaded if referenced from a container. Therefore, the loading order of the drivers will depend on their start up order.
Bootloader¶
To natively run Pantavisor on a device, it is necessary to have some on-disk artifacts that fall out of the umbrella of Pantavisor revisions. This is the case of the bootloader, which will load the Linux kernel and directly execute the initrd (Pantavisor) after that. Both the bootloader and Pantavisor will interact with Pantavisor storage to communicate with each other so the bootloader kwnows where to find the artifacts to boot.
We support a number of boards, using both U-Boot and GRUB bootloaders. These include all the bring up mechanisms that is necessary to run Pantavisor in its minimal form. You can take a look at the supported boards here. Contact us if you need support for your board!
In regards of how the interaction with the bootloader is done, Pantavisor can be set up to different modes using the PV_BOOTLOADER_TYPE config key:
uboot¶
In this mode, both Pantavisor and U-Boot will write and read to and from a file in storage that contains the revision information that U-Boot needs so it can boot up at any time. With that information, Kernel and initrd will be loaded from that same storage by U-Boot.
uboot-ab¶
This mode is similar to uboot but it will use fit images stored in two mtd partitions so the Kernel can be loaded in a faster manner by the bootloader. The selection of the partition to be booted is done by Pantavisor using U-Boot env variables, as well as the writing of the Kernel images in each partition.
This mode can be tuned up with the following config keys:
PV_BOOTLOADER_UBOOTAB_A_NAMEPV_BOOTLOADER_UBOOTAB_B_NAMEPV_BOOTLOADER_UBOOTAB_ENV_NAMEPV_BOOTLOADER_UBOOTAB_ENV_BAK_NAMEPV_BOOTLOADER_UBOOTAB_ENV_OFFSETPV_BOOTLOADER_UBOOTAB_ENV_SIZE
rpiab¶
This mode sets Pantavisor up to work with tryboot_a-b for Raspberry Pi.
grub¶
In this mode, both Pantavisor and GRUB will write and read to and from a file in storage that contains the revision information that GRUB needs to boot up at any moment. With that information, Kernel and initrd will be loaded from that same storage by GRUB.