On Thu, Nov 5, 2020 at 9:58 AM Alex Bennée alex.bennee@linaro.org wrote:
Signed-off-by: Alex Bennée alex.bennee@linaro.org
docs/system/guest-loader.rst | 54 ++++++++++++++++++++++++++++++++++++ docs/system/index.rst | 1 + 2 files changed, 55 insertions(+) create mode 100644 docs/system/guest-loader.rst
diff --git a/docs/system/guest-loader.rst b/docs/system/guest-loader.rst new file mode 100644 index 0000000000..37d03cbd89 --- /dev/null +++ b/docs/system/guest-loader.rst @@ -0,0 +1,54 @@ +..
- Copyright (c) 2020, Linaro
+Guest Loader +------------
+The guest loader is similar to the `generic-loader` although it is +aimed at a particular use case of loading hypervisor guests. This is +useful for debugging hypervisors without having to jump through the +hoops of firmware and boot-loaders.
+The guest loader does two things:
- load blobs (kernels and initial ram disks) into memory
- sets platform FDT data so hypervisors can find and boot them
+This is what is typically done by a boot-loader like grub using it's +multi-boot capability. A typical example would look like:
+.. parsed-literal::
- |qemu_system| -kernel ~/xen.git/xen/xen \
- -append "dom0_mem=1G,max:1G loglvl=all guest_loglvl=all" \
- -device guest-loader,addr=0x42000000,kernel=Image,bootargs="root=/dev/sda2 ro console=hvc0 earlyprintk=xen" \
- -device guest-loader,addr=0x47000000,initrd=rootfs.cpio
+In the above example the Xen hypervisor is loaded by the -kernel +parameter and passed it's boot arguments via -append. The Dom0 guest +is loaded into the areas of memory. Each blob will get +`/chosen/module@<addr>` entry in the FDT to indicate it's location and +size. Additional information can be passed with by using additional +arguments.
+Currently the only supported machines which use FDT data to boot are +the ARM and RiscV `virt` machines.
RISC-V.
Otherwise:
Reviewed-by: Alistair Francis alistair.francis@wdc.com
Alistair
+Arguments +^^^^^^^^^
+The full syntax of the guest-loader is::
- -device guest-loader,addr=<addr>[,kernel=<file>,[bootargs=<args>]][,initrd=<file>]
+``addr=<addr>``
- This is mandatory and indicates the start address of the blob.
+``kernel|initrd=<file>``
- Indicates the filename of the kernel or initrd blob. Both blobs will
- have the "multiboot,module" compatibility string as well as
- "multiboot,kernel" or "multiboot,ramdisk" as appropriate.
+``bootargs=<args>``
- This is an optional field for kernel blobs which will pass command
- like via the `/chosen/module@<addr>/bootargs` node.
diff --git a/docs/system/index.rst b/docs/system/index.rst index 3cff0ca98f..b5cfe8ee93 100644 --- a/docs/system/index.rst +++ b/docs/system/index.rst @@ -25,6 +25,7 @@ Contents: ivshmem linuxboot generic-loader
- guest-loader vnc-security tls gdb
-- 2.20.1