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This commit makes bbl read some additional fields from
the device tree if it detects an ns16550a:
- reg-shift
- reg-offset
- clock-frequency
For explanation of these check out the Linux Kernel doc:
https://www.kernel.org/doc/Documentation/devicetree/bindings/serial/8250.txt
In particular this allows the Xilinx AXI UART 16550 to act
as serial console with bbl and the Linux early boot console.
This also fixes a bug in which bbl will ignore any other than the first
"compatible" string when iterating over the nodes.
Previously this line would not have worked:
compatible = "xlnx,xps-uart16550-2.00.a", "ns16550a";
Before bbl would have just checked the first field instead of checking
all strings in the list.
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Support for separate firmware and kernel payload is added
by updating BBL to read optional preloaded kernel address
attributes from device-tree using a similar mechanism to
that used to pass init ramdisk addresses to linux kernel.
chosen {
riscv,kernel-start = <0x00000000 0x80200000>;
riscv,kernel-end = <0x00000000 0x80590634>;
};
These attributes are added by QEMU and read by BBL when combining
-bios <firmware-image> and -kernel <kernel-image> options. e.g.
$ qemu-system-riscv64 -machine virt -bios bbl -kernel vmlinux
With this change, bbl can be compiled without --with-payload
and the dummy payload alignment is altered to make the memory
footprint of the firmware-only bbl smaller. The dummy payload
message is updated to indicate the alternative load method.
This load method could also be supported by a first stage boot
loader that reads seperate firmware and kernel from SPI flash.
The main advantage of this new mechanism is that it eases kernel
development by avoiding the riscv-pk packaging step after kernel
builds, makes building per repository artefacts for CI simpler,
and mimics bootloaders on other platforms that can load a kernel
image file directly. Ultimately BBL should use an SPI driver to
load the kernel image however this mechanism supports use cases
such such as QEMU's -bios, -kernel and -initrd options following
examples from other platforms that pass kernel entry to firmware
via device-tree.
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Alistair Francis <Alistair.Francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
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This checks to see if a hart can't boot Linux by looking for a
compatible "mmu-type" field. If the hart can't boot Linux, then bbl
masks it off.
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I'm trying to debug some device tree problems while booting Linux and
figured it would be really nice to have access to the device tree while
trying to debug these problems. I think this might be useful for lots
of people, so I went ahead and cleaned up the code enough that it should
actaully work in most cases.
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This fixes RV32 pk.
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The clint was wiping out information discovered by the plic.
Initialize hart stacks as they are discovered.
Then fill in clint+plic info
Then wake the harts.
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