Date: Mon, 23 Aug 2010 15:07:30 -0700 From: mdf@FreeBSD.org To: Marcel Moolenaar <marcelm@juniper.net> Cc: FreeBSD Arch <freebsd-arch@freebsd.org> Subject: Re: RFC: enhancing the root mount logic Message-ID: <AANLkTikLd0-sLN=oxobC03yKfNcZ7mHguQNtooojOE=B@mail.gmail.com> In-Reply-To: <AFBE2FCA-30A6-4E1D-A964-AC4DC4C843EB@juniper.net>
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On Mon, Aug 23, 2010 at 2:30 PM, Marcel Moolenaar <marcelm@juniper.net> wrote:
> In embedded products, software is possibly installed as an image onto
> an actual storage device. This means that mounting the storage device
> as root is not enough to have a usable root file system. The rough
> draft below is an idea to enhance the root mount from having ad-hoc
> quirks to a well-defined and recursive mechanism to allow a wide-
> range of use cases.
I am not making any claims to the overall desirability of this, but as
a suggestion for the file format:
> [devfs] /.mount.conf:
> ufs:/dev/da0
> .ask
> .wait 5
> .onfail panic
To me, this should wait 0 seconds (or whatever the default is) until
after the .ask mount point has been tried.
I'd suggest something like:
[devfs] /.mount.conf:
.wait 10
ufs:/dev/da0
# wait up to 10 seconds for ufs
.wait 5
.ask
# wait up to 5 seconds for the prompt-returned filesystem
.onfail panic
The two reasons for such a usage:
1) simplifies parsing, since the file only needs to be read to a mount
directive, not read in its entirety.
2) allows different timeouts for each root mount location
I could also imagine, instead, a .mount directive, so that all
"commands" start with a '.' which would be like:
.mount ufs:/dev/da0 8
which would be an 8 second timeout on the specified mount point.
Anyways, as a flexible mechanism this sounds reasonable. I have no
idea how it compares to what other operating systems do, which is only
relevant insofar as making migration from another platform easier.
Thanks,
matthew
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