Git port to Debian SH4 may have trouble

> (sh4) debian-chroot:~# git clone -vv https://github.com/weidai11/cryptopp
> Cloning into 'cryptopp'...
> POST git-upload-pack (175 bytes)
> want e9cbc4698a6b3ed067910862ad1355069f348d2b (HEAD)
> want e9cbc4698a6b3ed067910862ad1355069f348d2b (refs/heads/master)
> ...
> want 511806c0eba8ba5b5cedd4b4a814e96df92864a6 (refs/tags/CRYPTOPP_8_7_0)
> POST git-upload-pack (gzip 1602 to 825 bytes)
> remote: Enumerating objects: 28448, done.
> remote: Counting objects: 100% (68/68), done.
> remote: Compressing objects: 100% (50/50), done.
> remote: Total 28448 (delta 29), reused 49 (delta 18), pack-reused 28380
> Receiving objects: 100% (28448/28448), 27.01 MiB | 4.30 MiB/s, done.
> Resolving deltas:   0% (0/20757)
> ^Cfatal: fetch-pack: invalid index-pack output

>
> On Tue, Nov 29, 2022 at 12:01:01PM -0500, Jeffrey Walton wrote:
>
> > This is a crummy bug report... I am  testing on Debian Unstable within
> > a SH4 Chroot. I'm seeing a hang during a git pull. Eventually I have
> > to CTRL+C, which results in "fatal: fetch-pack: invalid index-pack
> > output."
>
> The message is probably a red herring. Once you terminate index-pack,
> the fetch-pack process reading from it will see EOF before reading the
> expected "pack ..." line, and generate that message.
>
> So the hang is probably the only interesting part.
>
> > (sh4) debian-chroot:~# git clone -vv https://github.com/weidai11/cryptopp
> > Cloning into 'cryptopp'...
> > POST git-upload-pack (175 bytes)
> > want e9cbc4698a6b3ed067910862ad1355069f348d2b (HEAD)
> > want e9cbc4698a6b3ed067910862ad1355069f348d2b (refs/heads/master)
> > ...
> > want 511806c0eba8ba5b5cedd4b4a814e96df92864a6 (refs/tags/CRYPTOPP_8_7_0)
> > POST git-upload-pack (gzip 1602 to 825 bytes)
> > remote: Enumerating objects: 28448, done.
> > remote: Counting objects: 100% (68/68), done.
> > remote: Compressing objects: 100% (50/50), done.
> > remote: Total 28448 (delta 29), reused 49 (delta 18), pack-reused 28380
> > Receiving objects: 100% (28448/28448), 27.01 MiB | 4.30 MiB/s, done.
> > Resolving deltas:   0% (0/20757)
> > ^Cfatal: fetch-pack: invalid index-pack output
>
> If we're in the "resolving deltas" section, then that means we're
> probably not hanging on receiving input from the remote side. At this
> point we should have gotten all of the data and would be CPU-bound
> reassembling deltas and computing their hashes.
>
> Just a hunch, but does:
>
>   git config --global pack.threads 1
>
> help? The delta resolution is multi-threaded, but nothing else in the
> clone should be.

> > Just a hunch, but does:
> >
> >   git config --global pack.threads 1
> >
> > help? The delta resolution is multi-threaded, but nothing else in the
> > clone should be.
> 
> Yes, `git config --global pack.threads 1` allowed things to continue.
> The check-out was successful.

>
> On Tue, Nov 29, 2022 at 04:49:30PM -0500, Jeffrey Walton wrote:
>
> > > Just a hunch, but does:
> > >
> > >   git config --global pack.threads 1
> > >
> > > help? The delta resolution is multi-threaded, but nothing else in the
> > > clone should be.
> >
> > Yes, `git config --global pack.threads 1` allowed things to continue.
> > The check-out was successful.
>
> OK, that narrows it down. The question then is why threads don't work.
> Is there something broken with threading or luck primitives on that
> platform? Or are we doing something sketchy with concurrency that
> happens to work on Intel but not elsewhere, and we end up in some kind
> of deadlock?