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Differential D5332

Document vfs.root.mountfrom
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Authored by sobomax on Feb 18 2016, 8:56 PM.
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rS297690: Document vfs.root.mountfrom.
Summary

It's rather important option if you use for anything more advanced than plain PC. Over the years I found it's extremely strange that such important option is not documented at all.

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sobomax updated this revision to Diff 13440.Feb 18 2016, 8:56 PM
sobomax retitled this revision from to Document vfs.root.mountfrom.
sobomax updated this object.
sobomax edited the test plan for this revision. (Show Details)
sobomax added a reviewer: manpages.
sobomax set the repository for this revision to rS FreeBSD src repository - subversion.
sobomax added subscribers: wblock, imp.
Herald edited edge metadata. · View Herald TranscriptFeb 18 2016, 8:56 PM
wblock added inline comments.Feb 18 2016, 9:50 PM
sys/boot/forth/loader.conf.5
116

That seems a little confusing. By definition, it has to be in a way the kernel understands. How about just:

Specify the root partition to mount.
121

"Normally" is not needed:

The value of this tunable is automatically set by
125

How about

This parameter can be set manually when the calculated
value is not correct.
That can happen when
.Pa /etc/fstab
is inaccessible at the time
.Xr loader 8
runs, like during diskless booting from NFS.
imp added inline comments.Feb 18 2016, 10:02 PM
sys/boot/forth/loader.conf.5
119

The preferred form is "ufs:/dev/da0s1a" and that should be documented.

131

It's also available when the 'guessed' /etc/fstab that's read is known to be wrong.

sobomax added a child revision: D5333: Improve mkuzip(8) and geom_uzip(4), merge in LZMA support from mkulzma(8) and geom_uncompress(4).Feb 18 2016, 10:14 PM
sobomax updated this revision to Diff 13450.Feb 18 2016, 11:23 PM
sobomax edited edge metadata.
sobomax marked 5 inline comments as done.

Include suggestions from @imp and @wblock

Herald edited edge metadata. · View Herald TranscriptFeb 18 2016, 11:23 PM
sobomax added a comment.Feb 18 2016, 11:23 PM

Done, new diff is up please check. Thanks!

sys/boot/forth/loader.conf.5
125

Accepted, mostly, I've dropped "manually" since we are talking about loader.conf, since it might pretty well be permanent override, while "manually" to me implies doing it via loader's CLI. Also blended in with some of the @imp's comments below. Please check the new revision.

131

Blended with some of the suggestions from wblock above. It becomes quite long, not sure if something can be dropped without reducing the clarity.

wblock added inline comments.Feb 19 2016, 3:21 AM
sys/boot/forth/loader.conf.5
125

The problem is that "can be set" is vague about who is doing the setting, the user or the system. Maybe "can be set by the user"?

And "is known to be incorrect" is not really different from just "incorrect".

126

Not really clear what this means. Possibly there are too many things being combined and it would be easier to separate them.
Is this any better?

.Xr loader 8
automatically calculates the value of this tunable from
.Pa /etc/fstab .
The calculated value can be incorrect when
.Pa /etc/fstab
is not available during
.Xr loader 8
startup (as during diskless booting from NFS), or if a different
device is desired by the user.
The preferred value can be set in
.Pa /loader.conf .
138

This should probably be two sentences:

The value can also be overridden from the
.Xr loader 8
command line.
This is useful for system recovery when
.Pa /etc/fstab
is damaged, lost, or read from the wrong partition.
sobomax updated this revision to Diff 13656.Feb 23 2016, 7:41 PM
sobomax edited edge metadata.

commit aac88dd0e247cc7392b40e07750c338113faded1
Author: Maksym Sobolyev <sobomax@sippysoft.com>
Date: Thu Feb 18 15:21:05 2016 -0800

Include suggestions from @imp and @wblock.
Herald edited edge metadata. · View Herald TranscriptFeb 23 2016, 7:41 PM
sobomax updated this revision to Diff 13657.Feb 23 2016, 7:50 PM
sobomax edited edge metadata.
sobomax marked an inline comment as done.

commit 38a3f85028494f7f5a6b361467a544d3363f35e6
Author: Maksym Sobolyev <sobomax@sippysoft.com>
Date: Tue Feb 23 11:47:58 2016 -0800

Some more fixes from @wblock.
Herald edited edge metadata. · View Herald TranscriptFeb 23 2016, 7:50 PM
sobomax marked 3 inline comments as done.Feb 23 2016, 7:51 PM
wblock added a comment.Feb 26 2016, 5:14 AM

Remember that .Dd must be updated. Always good to run igor -R loader.conf.5 | less -RS and mandoc -Tlint loader.conf.5, too.

sys/boot/forth/loader.conf.5
124

"can be incorrect" is easy to read as "is allowed to be wrong", but really means "might be calculated incorrectly".

126

Missing an "is" for "is not".

imp accepted this revision.Feb 26 2016, 6:57 AM
imp added a reviewer: imp.

One final niggle.

sys/boot/forth/loader.conf.5
124

You might want to add after /etc/fstab "from the partition the kernel was loaded from" to be specific about how it finds /etc/fstab to look at.

This revision is now accepted and ready to land.Feb 26 2016, 6:57 AM
sobomax marked 3 inline comments as done.Apr 8 2016, 12:15 AM
Closed by commit rS297690: Document vfs.root.mountfrom. (authored by sobomax). · Explain WhyApr 8 2016, 12:24 AM
This revision was automatically updated to reflect the committed changes.

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sys/
boot/
forth/
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Diff 13657

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sys/boot/forth/loader.conf.5

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