contains one. Published dts source often includes a minimal default
memory definition and expects it to be overridden by the bootloader after
determining the actual physical memory in the system.
Implement a subset of the multiboot specification in order to boot Xen
and a FreeBSD Dom0 from the FreeBSD bootloader. This multiboot
implementation is tailored to boot Xen and FreeBSD Dom0, and it will
most surely fail to boot any other multiboot compilant kernel.
In order to detect and boot the Xen microkernel, two new file formats
are added to the bootloader, multiboot and multiboot_obj. Multiboot
support must be tested before regular ELF support, since Xen is a
multiboot kernel that also uses ELF. After a multiboot kernel is
detected, all the other loaded kernels/modules are parsed by the
multiboot_obj format.
The layout of the loaded objects in memory is the following; first the
Xen kernel is loaded as a 32bit ELF into memory (Xen will switch to
long mode by itself), after that the FreeBSD kernel is loaded as a RAW
file (Xen will parse and load it using it's internal ELF loader), and
finally the metadata and the modules are loaded using the native
FreeBSD way. After everything is loaded we jump into Xen's entry point
using a small trampoline. The order of the multiboot modules passed to
Xen is the following, the first module is the RAW FreeBSD kernel, and
the second module is the metadata and the FreeBSD modules.
Since Xen will relocate the memory position of the second
multiboot module (the one that contains the metadata and native
FreeBSD modules), we need to stash the original modulep address inside
of the metadata itself in order to recalculate its position once
booted. This also means the metadata must come before the loaded
modules, so after loading the FreeBSD kernel a portion of memory is
reserved in order to place the metadata before booting.
In order to tell the loader to boot Xen and then the FreeBSD kernel the
following has to be added to the /boot/loader.conf file:
xen_cmdline="dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga"
xen_kernel="/boot/xen"
The first argument contains the command line that will be passed to the Xen
kernel, while the second argument is the path to the Xen kernel itself. This
can also be done manually from the loader command line, by for example
typing the following set of commands:
OK unload
OK load /boot/xen dom0_mem=1024M dom0_max_vcpus=2 dom0pvh=1 console=com1,vga
OK load kernel
OK load zfs
OK load if_tap
OK load ...
OK boot
Sponsored by: Citrix Systems R&D
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D517
For the Forth bits:
Submitted by: Julien Grall <julien.grall AT citrix.com>
moving U-Boot specific code from libfdt.a to a new libuboot_fdt.a. This
needs to be a new library for linking to work correctly.
Differential Revision: https://reviews.freebsd.org/D1054
Reviewed by: ian, rpaulo (earlier version)
MFC after: 1 week
by having uboot_autoload() do the fdt setup (which may load a file) rather
than waiting until we're actually in the process of launching the kernel.
As part of making this happen...
- Define LOADER_FDT_SUPPORT on the uboot/lib compile command line when
MK_FDT is set.
- Make fdt_setup_fdtb() public.
- Declare public fdt_whatever() functions in a header instead of using
scattered extern decls in .c files.
The name is taken from the u-boot env vars fdtfile or fdt_file. If the
name isn't fully-qualified a search is done in module_path locations.
The search order for a usable dtb in fdt_setup_fdtp() is now
- A dtb loaded with an explicit "load -t dtb" command.
- A dtb already loaded into memory somehow[*] and pointed to by fdt_to_load.
- A dtb in the memory pointed to by the u-boot env vars fdtaddr or fdt_addr.
- A file named by the u-boot env vars fdtfile or fdt_file.
- A static dtb compiled into the kernel.
* Presumably by some arch-specific command or code.
The old code basically said it was going to use some particular blob
without knowing whether it could successfully do so, then it would invoke
the function to do that and return its status. If it failed, you were
done, even if other blobs might be available. Now the code attempts to use
some particular blob and if that succeeds it says so and returns success,
otherwise it moves on to try another potential blob.
One specific problem this solves is when u-boot sets an fdtaddr variable
to point to some memory address, then doesn't actually load a blob at
that address. Now the header check will fail, and the code will move
on to the fallback dtb compiled into the kernel (if any).
source shows that board vendors seem to be about evenly split on this.
This commit is a trivial change to note that while the previous change
was supposed to be whitespace only, this functional change also crept in.
The added lines were:
/* Board vendors use both fdtaddr and fdt_addr names. Grrrr. */
if (s == NULL)
s = ub_env_get("fdt_addr");
While here, don't overwrite the error message on interactive use and add
the missing '\n' at end of error message for the non interactive use.
Tested by: ian, myself
Approved by: adrian (mentor, implicit)
they can easily be used by later post-processing. When searching for
a compiled-in fdt blob, use the section headers to get the size and
location of the .dynsym section to do a symbol search.
This fixes a problem where the search could overshoot the symbol
table and wander into the string table. Sometimes that was harmless
and sometimes it lead to spurious panic messages about an offset
bigger than the module size.
After digging through more carefully, it looks like there's
no real need to have the DTB in the module directory.
So we can simplify a lot: Just copy DTB into local heap
for "fdt addr" and U-Boot integration, drop all the extra
COPYIN() calls.
I've left one final COPYIN() to update the in-kernel DTB
for consistency with how this code used to work, but I'm
no longer convinced it's appropriate here.
I've also remove the mem_load_raw() utility that I added
to boot/common/module.c with r247045 since it's no longer
necessary.
This was broken by r247045 which tried to copy the FDT into the
module directory immediately.
Instead, store the address and arrange for the FDT to get
copied into the module directory later when the usual
FDT initialization runs.
When initializing the fdt, query U-Boot as well.
With this change, it is now feasible to have U-Boot load
the FDT, ubldr will pull it from U-Boot and hand it to the
kernel.
- Add "fdt addr" subcommand that lets you specify preloaded blob address
- Do not pre-initialize blob for "fdt addr"
- Do not try to load dtb every time fdt subcommand is issued,
do it only once
- Change the way DTB is passed to kernel. With introduction of "fdt addr"
actual blob address can be not virtual but physical or reside in
area higher then 64Mb. ubldr should create copy of it in kernel area
and pass pointer to this newly allocated buffer which is guaranteed to work
in kernel after switching on MMU.
- Convert memreserv FDT info to "memreserv" property of root node
FDT uses /memreserve/ data to notify OS about reserved memory areas.
Technically it's not real property, it's just data blob, sequence
of <start, size> pairs where both start and size are 64-bit integers.
It doesn't fit nicely with OF API we use in kernel, so in order to unify
thing ubldr converts this data to "memreserve" property using the same
format for addresses and sizes as /memory node.
The code previously assumed that copyin/copyout did no
address translation and that the device tree blob could
be manipulated in-place (with only a few adjustments for
the ELF loader offset). This isn't possible on all platforms,
so the revised code uses copyout() to copy the device tree
blob into a heap-allocated buffer and then updates the
device tree with copyout(). This isn't ideal, since it
bloats the loader memory usage, but seems the only feasible
approach (short of rewriting all of the fdt manipulation
routines).
o Fix buffer overflows when using a long property body in node paths.
o Fix loop end condition when iterating through the symbol table.
o Better error handling during node modification, better problem reporting.
o Eliminate build time warnings.
Submitted by: Lukasz Wojcik
Obtained from: Semihalf
MFC after: 1 week
Enable using the statically embedded blob from the kernel, if present. The KLD
loaded DTB takes precedence, but they are both recognized and handled in the
same way.
Submitted by: Lukasz Wojcik
Obtained from: Semihalf
MFC after: 1 week
o This is disabled by default for now, and can be enabled using WITH_FDT at
build time.
o Tested with ARM and PowerPC.
Reviewed by: imp
Sponsored by: The FreeBSD Foundation
