From: alex-ml@posteo.de
To: 9front@9front.org
Subject: [9front] Reform MNT Boot Process
Date: Mon, 12 Feb 2024 08:17:22 +0000 [thread overview]
Message-ID: <1ef18420c4f54c9155a18c7d6dd16ca5@posteo.de> (raw)
Hello everyone,
I am new to Plan 9 / 9front and am trying to understand the system.
Since I'm using an MNT Reform, I'm particularly interested in the
aarch64 architecture. As a starting point, I'm reading the Plan 9 3rd
Edition Kernel Notes (is there by any chance a way to get the
assignments mentioned therein?).
I can't find 9boot or 9load in /sys/src/boot/reform/, so I wonder
whether there is another way to load the kernel?
The notes state:
"The boot process starts when you press the power button on your PC. The
BIOS (a program in ROM) is instructed to search for several devices to
boot from. Usually, it will search for a floppy disk unit, a cdrom unit,
and a hard disk. Once the boot device is located, the BIOS loads a block
from the device. For hard disks, it loads the Master Boot Record (MBR),
for floppies, it loads the boot sector (PBS).
Once either the MBR or the PBS get loaded, the BIOS jumps to its
starting address. The BIOS is done. Both MBR and PBS contain a tiny
program that proceeds the loading process. The MBR scans the partition
table for active partitions and loads the PBS sector of the active
partition. Thus, all in all, we end up with the PBS loaded in memory.
Plan 9 supplies its own PBS program. It will load the program 9load
which will continue the job."
My guess would be that flash.bin (built via the mkfile) is loading the
kernel with the information from boot.scr (also built via mkfile). Is
that right? In this case, the boot process would be a bit easier than
described above (at least with fewer steps).
In /sys/src/cmd/aux/txt2uimage.c/, which is used in the recipe for
boot.scr, there are some numbers that I would like to understand where
they come from. Is there some documentation explaining how an uimage and
/ or header has to look like? Unfortunately I wasn't able to find this
information on https://docs.u-boot.org/.
And the same question for /sys/src/boot/reform/boot.txt/, where some
addresses are given. How do I obtain this information?
I am very sorry for my beginner questions and I would really appreciate
any explanations/hints to help me understand what happens during the
boot process.
Thank you very much in advance!
next reply other threads:[~2024-02-12 8:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-12 8:17 alex-ml [this message]
2024-02-12 13:52 ` Sigrid Solveig Haflínudóttir
2024-02-12 14:01 ` Sigrid Solveig Haflínudóttir
2024-02-13 7:25 ` alex-ml
2024-02-13 8:53 ` alex-ml
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