vendor/illumos merges

[Ulrich Spörlein]

On Fri, 2021-04-23 at 17:26:33 -0400, Mark Johnston wrote:
>Hi,
>
>Now that FreeBSD uses OpenZFS as the upstream for ZFS, vendor/illumos is
>mostly unused.  However, we still use illumos as an upstream for CTF
>tools and DTrace, though there haven't been any imports in a while.
>
>illumos has put a lot of work into their CTF toolchain, and I'd like to
>import that.  There are a couple of snags that I'd appreciate some
>guidance on.
>
>First, I believe I should delete now-unused ZFS code from the vendor
>branch and merge the result to main.  I did this locally and got an
>empty merge, which is what I'd expect.  Is there any problem with this?

Why would you record this empty merge? If you clean up vendor/foo, just 
do that but don't merge a no-op back into main (nothing changed, after 
all).

>Second, with Subversion we had both vendor/illumos and
>vendor-sys/illumos, and now we just have the former, seemingly with
>sys/* bits imported from vendor-sys.  Some of the upstream commits touch
>both userspace and kernel bits, but the merge targets for these in
>FreeBSD are different: cddl/contrib/opensolaris vs.
>sys/cddl/contrib/opensolaris.  How should I merge into main in this
>case?  I don't really see any options other than to split each offending
>upstream commit into two parts, one for userspace and one for the
>kernel, and merge them separately.
>
>If it helps to look at the branch where I staged the upstream commits,
>I've pushed it to vendor/illumos2 in https://github.com/markjdb/freebsd
>.

Can you clarify why the merging of the two might be an issue? Note that 
unlike subversion, in git there's no "merge a certain subtree" handling, 
all that is recorded is a tree of some form and then a set of parents or 
ancestor commits. (git is a content tracker, not really a VCS :)

I was under the impression that userland and kernel imports/merges need 
to happen at the same time anyway, so I assume you would import all the 
bits under vendor/foo in 1 commit and then merge them in 1 commit into 
main. Is that not how it goes?

Cheers
Uli