Re: Getting /usr/src to match specific git hash?

On Sun, Jan 24, 2021 at 09:00:45AM -0700, Warner Losh wrote:
> On Sun, Jan 24, 2021, 6:05 AM Jeffrey Bouquet <jbtakk_at_iherebuywisely.com>
> wrote:
> 
> >
> >
> > On Sat, 23 Jan 2021 20:14:03 -0800, Steve Kargl <
> > sgk_at_troutmask.apl.washington.edu> wrote:
> >
> > > On Sun, Jan 24, 2021 at 01:08:05PM +0900, Yasuhiro Kimura wrote:
> > > > From: Steve Kargl <sgk_at_troutmask.apl.washington.edu>
> > > > Subject: Getting /usr/src to match specific git hash?
> > > > Date: Sat, 23 Jan 2021 19:58:52 -0800
> > > >
> > > > > Suppose one has an empty /usr/src.
> > > > >
> > > > > Suppose further that one had to re-install a 32-bit
> > > > > i386-*-freebsd with the 24 Dec 2020 image available
> > > > > from freebsd.org.
> > > > >
> > > > > uname -a for the booted kernel shows
> > > > >
> > > > > % uname -a
> > > > > FreeBSD mobile 13.0-CURRENT FreeBSD 13.0-CURRENT #0 \
> > > > > 3cc0c0d66a0-c255241(main)-dirty: Thu Dec 24 05:43:23 UTC 2020 \
> > > > > root_at_releng1.nyi.freebsd.org:/usr/obj/usr/src/i386.i386/sys/GENERIC
> > i386
> > > > >
> > > > > How does one use git to pull the exact sources that match
> > > > > this specifc kernel?
> > > >
> > > > cd /usr
> > > > git clone https://git.freebsd.org/src.git
> > > > cd src
> > > > git checkout 3cc0c0d66a0
> > > >
> > >
> > > Thank you.
> > >
> >
> > Can this be put in /usr/src/UPDATING with an explanation of precisely how
> > each
> > of the git commands populates or repopulated the directories in /usr???
> >
> 
> It is in the mini primer I wrote, along with how to bisect and other useful
> things. This will migrate into the handbook once the doc tree converts to
> asciidoc (happening this weekend).
> 
> https://github.com/bsdimp/freebsd-git-docs/blob/main/mini-primer.md
> 

Any advice on how to jump, say, 4 days ahead of the current
date of the src/ tree?  That is, I have src/ that should
correspond to 24 Dec 2020.  How do I jump to 28 Dec 2020?

My past week experience with top-of-tree suggests doing
a bisection would be frought with peril.  My laptop runs
well with 24 Dec 2020 kernel/world.  Getting to top-of-tree,
one has to deal with
(1) infinite recursion in wpa_supplicant,
(2) possible locking issue in UFS (30 second system freezes),
(3) memory alignment messages from the kernel,
(4) processes being killed with out-of-swapspace messages
    even though I have 4 GB of untouched swap space.  Might
    be associated with (3).
(5) graphic console mess
(6) pilot-error of using -march=core2, which matches the
    processor in the laptop, to build kernel/world but
    manifests a llvm bug

I would like to creep up on the issues.
 
-- 
Steve