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sparc docs: write down some more useful things

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These are better here than in my bash history...

Change-Id: Iab8940f4efed950e26a8bad29cb8954464270e8f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4645
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
This commit is contained in:
PulkoMandy 2021-10-22 20:49:28 +02:00 committed by waddlesplash
parent 6711cd9e9e
commit d1ecc0955f
1 changed files with 34 additions and 0 deletions
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34
docs/develop/kernel/arch/sparc/overview.rst
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@ -281,6 +281,23 @@ Configuring openboot for serial port
Boot from network
-----------------
The openboot bootloader supports network booting. See the
`Network booting guide <https://www.haiku-os.org/guides/network_booting/>`_
for general information about the general network booting process. This page
documents the parts specific to the openboot bootloader configuration.
In openboot, booting from the network is done simply by using the "net:" device
alias in the boot command line. This lets openboot load our bootloader, which
then uses the openboot ability to send and receive data over the network to load
the filesystem (and kernel contained in it) over the network. The two parts are
independent: it's also possible to load the bootloader from the network but boot
a local filesystem, or use the local bootloader and load the filesystem from the
network.
The bootloader needs to be placed in a tftp server, I use atftpd in Debian,
which serve files from /srv/tftp/ (so "somefile" in the example below will look
for /srv/tftp/somefile).
static ip
*********
@ -310,6 +327,11 @@ the boot file from there.
(net is an alias to the network card and also sets the load address: /pci@1f,4000/network@1,1)
This currently does not work completely: the server address is not forwarded to
the bootloader, and as a result, remote filesystems will not be available. The
bootloader needs to be updated to know where to find the address in this case
(it is done for PowerPC, I think).
dhcp
****
@ -325,6 +347,8 @@ the file to load and boot.
Debugging
---------
The openboot environment provide several useful commands to assist in debugging:
.. code-block:: text
202000 dis (disassemble starting at 202000 until next return instruction)
@ -333,3 +357,13 @@ Debugging
.locals (show local/windowed registers)
%pc dis (disassemble code being exectuted)
ctrace (backtrace)
The backtrace provides addresses and register values (allowing to know the
function arguments), there is no symbols and function names printed.
objdump (on the build machine) can be used to disassemble the kernel or
bootloader and find the corresponding code:
.. code-block:: text
./cross-tools-sparc/bin/sparc64-unknown-haiku-objdump -d objects/haiku/sparc/release/system/kernel/kernel_sparc |c++filt|less
./cross-tools-sparc/bin/sparc64-unknown-haiku-objdump -d objects/haiku/sparc/release/system/boot/openfirmware/boot_loader_openfirmware |c++filt|less