Use the shared initrd reshuffling and CPIO header construction code
for RISC-V bare-metal kernels. This allows for files to be injected
into the constructed ("magic") initrd image in exactly the same way as
is done for bzImage and UEFI kernels.
We append a dummy image encompassing the FDT to the end of the
reshuffle list, so that it ends up directly following the constructed
initrd in memory (but excluded from the initrd length, which was
recorded before constructing the FDT).
We also temporarily prepend the kernel binary itself to the reshuffle
list. This is guaranteed to be safe (since reshuffling is designed to
be unable to fail), and avoids the requirement for the kernel segment
to be available before reshuffling. This is useful since current
RISC-V bare-metal kernels tend to be distributed as EFI zboot images,
which require large temporary allocations from the external heap for
the intermediate images created during archive extraction.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow a single initrd image to be passed verbatim to the booted RISC-V
kernel, as a proof of concept.
We do not yet support reshuffling to make optimal use of available
memory, or dynamic construction of CPIO headers, but this is
sufficient to allow iPXE to start up the Fedora 42 kernel with its
matching initrd image.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Allow an initrd location to be specified in our constructed device
tree via the "linux,initrd-start" and "linux,initrd-end" properties.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Current RISC-V and AArch64 kernels found in the wild tend not to be in
the documented kernel format, but are instead "EFI zboot" kernels
comprising a small EFI executable that decompresses and executes the
inner payload (which is a kernel in the expected format).
The EFI zboot header includes a recognisable magic value "zimg" along
with two fields describing the offset and length of the compressed
payload. We can therefore treat this as an archive image format,
extracting the payload as-is and then relying on our existing ability
to execute compressed images.
This is sufficient to allow iPXE to execute the Fedora 42 RISC-V
kernel binary as currently published.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
The RISC-V and AArch64 bare-metal kernel images share a common header
format, and require essentially the same execution environment: loaded
close to the start of RAM, entered with paging disabled, and passed a
pointer to a flattened device tree that describes the hardware and any
boot arguments.
Implement basic support for executing bare-metal RISC-V and AArch64
kernel images. The (trivial) AArch64-specific code path is untested
since we do not yet have the ability to build for any bare-metal
AArch64 platforms. Constructing and passing an initramfs image is not
yet supported.
Rename the IMAGE_BZIMAGE build configuration option to IMAGE_LKRN,
since "bzImage" is specific to x86. To retain backwards compatibility
with existing local build configurations, we leave IMAGE_BZIMAGE as
the enabled option in config/default/pcbios.h and treat IMAGE_LKRN as
a synonym for IMAGE_BZIMAGE when building for x86 BIOS.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
