[9fans] I did bad things and 9front won't boot

[9fans] I did bad things and 9front won't boot

[o]

Hello, 

I seem to have done incredibly stupid things to my 9front instance and now on boot I get "panic: unknown keyword in config block: <some character>", followed by a "mount: sys: write on closed pipe pc=0x2008c6" and "mount /srv/boot /root: mount 185: sys: write on closed pipe pc=0x2008c6”.

At this point I did try to drop into a shell, but I can’t figure out from there how I can mount my filesystem (that I can see in the list of things under /dev/sdE0/fsmain). 

By now I’ve also figured out that the panic is happening “here”, in the mergeconf function:
http://git.9front.org/plan9front/plan9front/858893ff8ff8d3abd06742276bcb794f3422bab8/sys/src/cmd/cwfs/config.c/f.html

Is there a way for me to rewrite the config block to sensible defaults by dropping into a shell and/or using a usb drive w/ 9front on it (as if doing an install) to just backstep whatever terrible thing I performed accidentally?

Thanks,

Olivier
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Re: [9fans] I did bad things and 9front won't boot

[qwx via 9fans]

On Thu Dec 21 02:54:25 +0100 2023, o@o5r.ca wrote:
> Hello, 
> 
> I seem to have done incredibly stupid things to my 9front instance and now on boot I get "panic: unknown keyword in config block: <some character>", followed by a "mount: sys: write on closed pipe pc=0x2008c6" and "mount /srv/boot /root: mount 185: sys: write on closed pipe pc=0x2008c6”.

What stupid things did you do to break it?


> Is there a way for me to rewrite the config block to sensible defaults by dropping into a shell and/or using a usb drive w/ 9front on it (as if doing an install) to just backstep whatever terrible thing I performed accidentally?
> 
> Thanks,
> 
> Olivier

Yes, see fqa 9.2.5 [1].  See also fsconfig(8) [2].  What you enter
here depends on your setup.

You may want to subscribe to the 9front mailing list [3] and ask
9front-specific questions there to get better help.

Cheers,
qwx

[1] http://fqa.9front.org/fqa9.html#9.2.5
[2] http://man.9front.org/8/fsconfig
[3] http://fqa.9front.org/fqa2.html#2.2

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Re: [9fans] I did bad things and 9front won't boot

[ori]

At a guess, you tried to run something like:

        mount /dev/sdXX/cache

which will try to negotiate a version with your raw disk data,
and write a Tversion message to the first block of your disk.
You want to mount the 9p service which lives in /srv/cwfs.

You can probably either write it back manually, or using the
fs recovery console, documented (er, kinda) in fsconfig(8).

For reference, the fsconfig should look like:
        
        filsys main c(/dev/sdN0/fscache)(/dev/sdN0/fsworm)
        filsys dump o
        filsys other (/dev/sdN0/other)
        noauth
        newcache
        blocksize 16384
        daddrbits 64
        indirblks 4
        dirblks 6
        namelen 144
        cpu% read -c 1024 /dev/sdN0/fscache
        service cwfs
        filsys main c(/dev/sdN0/fscache)(/dev/sdN0/fsworm)
        filsys dump o
        filsys other (/dev/sdN0/other)
        noauth
        newcache
        blocksize 16384
        daddrbits 64
        indirblks 4
        dirblks 6
        namelen 144


Quoth o@o5r.ca <o@o5r.ca>:
> Hello,
> 
> I seem to have done incredibly stupid things to my 9front instance and now on boot I get "panic: unknown keyword in config block: <some character>", followed by a "mount: sys: write on closed pipe pc=0x2008c6" and "mount /srv/boot /root: mount 185: sys: write on closed pipe pc=0x2008c6”.
> 
> At this point I did try to drop into a shell, but I can’t figure out from there how I can mount my filesystem (that I can see in the list of things under /dev/sdE0/fsmain).
> 
> By now I’ve also figured out that the panic is happening “here”, in the mergeconf function:
> http://git.9front.org/plan9front/plan9front/858893ff8ff8d3abd06742276bcb794f3422bab8/sys/src/cmd/cwfs/config.c/f.html
> 
> Is there a way for me to rewrite the config block to sensible defaults by dropping into a shell and/or using a usb drive w/ 9front on it (as if doing an install) to just backstep whatever terrible thing I performed accidentally?
> 
> Thanks,
> 
> Olivier

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Re: [9fans] I did bad things and 9front won't boot

[Olivier Tremblay]

Quoth ori@eigenstate.org:
> At a guess, you tried to run something like:
> 
>         mount /dev/sdXX/cache

That is exactly what I tried to do.  I was experimenting with writing
my own filesystem.  I also am new at writing C, I mostly have done Go
in my career so far.  I then made unfortunate life choices and decided
to put my compiled program in cpurc.local.  Program crashes, yours
truly tries to mount the filesystem because, you know, that's what one
does when they've only ever done Linux things, hilarity ensues.


That being said, I apparently managed to successfully use ed to put
the correct values (adapted from what you provided) in place in
/dev/sdE0/fsmain, which is the thing I had utterly destroyed.


Thanks for the help!

Olivier


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