linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Paul E. McKenney" <paulmck@kernel.org>
To: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
Cc: Randy Dunlap <rdunlap@infradead.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	rcu@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: next-20200528 - build error in kernel/rcu/refperf.c
Date: Fri, 29 May 2020 07:02:28 -0700	[thread overview]
Message-ID: <20200529140228.GZ2869@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <543040.1590729879@turing-police>

On Fri, May 29, 2020 at 01:24:39AM -0400, Valdis Klētnieks wrote:
> On Thu, 28 May 2020 21:48:18 -0700, Randy Dunlap said:
> 
> > > ERROR: modpost: "__aeabi_uldivmod" [kernel/rcu/refperf.ko] undefined!
> 
> Gaah.  And the reason I didn't spot Paul's post while grepping my linux-kernel
> mailbox is because *that* thread had a different undefined reference:
> 
> > > > > > > m68k-linux-ld: kernel/rcu/refperf.o: in function `main_func':
> > > > > > > >> refperf.c:(.text+0x762): undefined reference to `__umoddi3'
> 
> > Paul has already responded: (unfortunately)
> >
> > "So I am restricting to 64BIT for the time being.  Yeah, I know, lazy of
> > me.  ;-)"
> 
> It's the sort of issue that's well into "as long as it gets mostly fixed before
> it hits Linus's tree" territory.   I've seen lots of far worse work-arounds in
> the years since the 2.5.47 kernel. :)

Fair enough!

Also as noted on the other thread, in this case, doing this 64-bit
division the hard way shouldn't be a problem:  The performance test is
finished and nothing else is happening.  So I have to wonder whether it
would be possible to detect this based on some sort of link-time checking,
presumably in conjunction with -O0 to avoid confusing the whitelist with
compiler optimizations.

That would allow use of C-language "/" and "%" while still allowing
gratuitous uses to be questioned.

Hey, I can dream, can't I?  ;-)

							Thanx, Paul

  reply	other threads:[~2020-05-29 14:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-29  4:16 next-20200528 - build error in kernel/rcu/refperf.c Valdis Klētnieks
2020-05-29  4:48 ` Randy Dunlap
2020-05-29  5:24   ` Valdis Klētnieks
2020-05-29 14:02     ` Paul E. McKenney [this message]
2020-05-29 13:55 ` Paul E. McKenney

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200529140228.GZ2869@paulmck-ThinkPad-P72 \
    --to=paulmck@kernel.org \
    --cc=josh@joshtriplett.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rcu@vger.kernel.org \
    --cc=rdunlap@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=valdis.kletnieks@vt.edu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).