Re: [9fans] p9f mention of 9front

[Richard Miller <9fans@hamnavoe.com>]

steve@quintile.net:
> However if fossil fills up - because more has been written to it than
> it can hold or because snapshots have been turned on without a venti
> attached, it will crash badly and can (I believe) lose user data.

No, it won't lose data (except in the sense that incoming mail, for
example, can't be stored anywhere while the disk is full).  You can't
usually boot from a completely full fossil, but if you have a fallback
boot method (from a CD or USB drive, from a network, or a spare recovery
fossil partition) you can then start a fossil on the full partition, and
run snapclean and/or delete some files, and all will be well. Even if
fossil data was damaged, you could recover with flfmt from venti if you
had archiving turned on.

Also, nowadays it doesn't actually "crash" ... it just becomes difficult
to do anything when no fossil blocks can be allocated. If the fossil on
a networked server is full, you may not be able to log into it because
that would require some fossil blocks. But you can still recover from
a client terminal, by importing its /srv/fossil and using that to issue
a snapclean command, or a remove command to delete something.

> As I have understood it (others may correct me) the difference between
> cpu and terminal kernels is only the value one global variable (cpuserver)
> in the kernel, and the list of drivers compiled in - traditionally there
> was no graphics support in cpu kernels for example.

I have a version of the 4e kernel which functions as either cpu or terminal
depending on the setting of environment variable 'service' in plan9.ini or
cmdline.txt. It requires only a handful of lines to be added in
/sys/src/9/boot/boot.c to make that work. Nowadays kernel RAM is plentiful
enough that there's no real reason to configure different sets of devices
between terminal and cpu.


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