Re: [9fans] Problems installing 9legacy on bare metal (Thinkpad X60)

[Thaddeus Woskowiak <tswoskowiak@gmail.com>]

On Sun, Jan 23, 2022 at 5:44 AM Richard Miller <9fans@hamnavoe.com> wrote:
> > !rc (and the rest of the boot) is one of the first things implemented uniquely by 9front.
> 
> I think there's a little bit of confusion about different stages of booting.
> 
> The 9boot program loads the kernel. The original Plan 9 9boot is driven
> by configuration variables in a plan9.ini file. Cinap's rewritten 9boot
> adds the capability of interactively changing configuration variables from
> the console before loading the kernel. That's really useful, especially
> when experimenting with new kernels or new hardware. But 9boot does not
> contain a shell or a built-in file system, so it doesn't allow you to
> type !rc and get an interactive shell.
> 
> Once the kernel is loaded, the first thing it does is to execute the
> command /boot/boot from a small root filesystem which is built into the
> kernel. The main job of /boot/boot is to attach to the real root filesystem
> (on a local device or from a network server) and execute /$cputype/init to
> start the system. Historically the usual case is for /boot/boot to
> be a specialised program built from C source in /sys/src/9/boot. But it
> has always been possible to configure a kernel with a shell script as
> /boot/boot - see for example /sys/lib/sysconfig/ppc/boot for the PowerPC,
> or /sys/src/9/bcm/bootwifi.rc for a Raspberry Pi accessing its root file
> server via wifi.
> 
> So, using a shell script as /boot/boot is not unique to 9front. But
> with 9front, it has become the default. This means there's always a
> shell inside the kernel, along with a few commands, ready to use
> interactively when !rc is invoked - after the kernel is loaded, but
> before the final root filesystem is attached.
> 
> The kernel on the 9legacy install CD doesn't have a shell script as
> /boot/boot with the ability to invoke !rc. Perhaps it should. But that
> wouldn't have helped in this case. Yakku was stuck at the 'Boot from'
> prompt within /9boot, unable to find a kernel to boot.
> 

Richard,
Thank you for the detailed explanation. I misread the part about no
kernel and thought we made it to the boot prompt and could not figure
out the disk name. Mea culpa.

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