guest-loader.rst (1937B)
1.. 2 Copyright (c) 2020, Linaro 3 4Guest Loader 5------------ 6 7The guest loader is similar to the ``generic-loader`` although it is 8aimed at a particular use case of loading hypervisor guests. This is 9useful for debugging hypervisors without having to jump through the 10hoops of firmware and boot-loaders. 11 12The guest loader does two things: 13 14 - load blobs (kernels and initial ram disks) into memory 15 - sets platform FDT data so hypervisors can find and boot them 16 17This is what is typically done by a boot-loader like grub using it's 18multi-boot capability. A typical example would look like: 19 20.. parsed-literal:: 21 22 |qemu_system| -kernel ~/xen.git/xen/xen \ 23 -append "dom0_mem=1G,max:1G loglvl=all guest_loglvl=all" \ 24 -device guest-loader,addr=0x42000000,kernel=Image,bootargs="root=/dev/sda2 ro console=hvc0 earlyprintk=xen" \ 25 -device guest-loader,addr=0x47000000,initrd=rootfs.cpio 26 27In the above example the Xen hypervisor is loaded by the -kernel 28parameter and passed it's boot arguments via -append. The Dom0 guest 29is loaded into the areas of memory. Each blob will get 30``/chosen/module@<addr>`` entry in the FDT to indicate it's location and 31size. Additional information can be passed with by using additional 32arguments. 33 34Currently the only supported machines which use FDT data to boot are 35the ARM and RiscV ``virt`` machines. 36 37Arguments 38^^^^^^^^^ 39 40The full syntax of the guest-loader is:: 41 42 -device guest-loader,addr=<addr>[,kernel=<file>,[bootargs=<args>]][,initrd=<file>] 43 44``addr=<addr>`` 45 This is mandatory and indicates the start address of the blob. 46 47``kernel|initrd=<file>`` 48 Indicates the filename of the kernel or initrd blob. Both blobs will 49 have the "multiboot,module" compatibility string as well as 50 "multiboot,kernel" or "multiboot,ramdisk" as appropriate. 51 52``bootargs=<args>`` 53 This is an optional field for kernel blobs which will pass command 54 like via the `/chosen/module@<addr>/bootargs` node.