Date: Mon, 24 Nov 2014 21:18:21 +0100 From: Philip Paeps <philip@freebsd.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r274966 - head/sys/net Message-ID: <20141124201821.GY95784@rincewind.trouble.is> In-Reply-To: <20141124194022.GR47144@FreeBSD.org> References: <201411241400.sAOE0Srq063100@svn.freebsd.org> <20141124194022.GR47144@FreeBSD.org>
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On 2014-11-24 22:40:22 (+0300), Gleb Smirnoff <glebius@FreeBSD.org> wrote: > On Mon, Nov 24, 2014 at 02:00:28PM +0000, Philip Paeps wrote: > P> Author: philip > P> Date: Mon Nov 24 14:00:27 2014 > P> New Revision: 274966 > P> URL: https://svnweb.freebsd.org/changeset/base/274966 > P> > P> Log: > P> Add a sysctl `net.link.tap.deladdrs_on_close' to configure whether tap > P> should delete configured addresses and routes when the interface is > P> closed. Default is enabled (preserve current behaviour). > P> > P> MFC after: 1 week > > Any time I see yet another sysctl knob added I ask myself: what if I want > this feature on tap0 but doesn't want it on tap1? What if want it on host, > but doesn't want it on vmnet-enabled jail? Where from could I learn about > this sysctl if I am not subscribed to svn-src-*@? I admit that this one was a hack written in anger a while back. When I hacked this, I was struggling with a bunch of bhyve instances with fiddly point to point routes and every time I restarted a bhyve, I'd have to fix my routing table again. That got frustrating quickly. Not an excuse. Just an explanation. > Of course adding a sysctl knob is faster and easier for a FreeBSD hacker. > But is it a better for a FreeBSD user? Are we making OS for just ourselves? > > Look, we've got tapifioctl(). If you are too lazy to introduce new > ioctl command and code it support in ifconfig, in this case you can just > use any of IFF_LINK0, IFF_LINK1, IFF_LINK2 flag to toggle this feature > via SIOCSIFFLAGS. And then document it in tap(4). Note that I semi-purposely didn't document this in tap(4). I should have pointed that out in the commit message, sorry. When I wrote this, this summer, I meant to ask about the magical and very legacy-looking VMware vmnet hacks in the driver. Are those still relevant? Is there still a VMWare port that relies on this? What about the comment that legacy devfs cloning interferes with ssh(1) (added seven years ago), is that still true? > Finally, if later some developer comes and does it in a proper way, then > he would have a burden of supporting your sysctl for backwards compatibility, > because you very quickly MFCed it. > > P.S. I am sorry if my email sounds like old man's grumbling. No problem. I'm happy to fix this 'better'. Old men often grumble sense (I keep telling myself as I get older...). Philip -- Philip Paeps Senior Reality Engineer Ministry of Information
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