if_data size issues
Peter Wemm
peter at wemm.org
Thu Sep 2 12:20:08 PDT 2004
On Thursday 02 September 2004 10:23 am, Brooks Davis wrote:
> On Thu, Sep 02, 2004 at 02:05:00AM -0600, M. Warner Losh wrote:
> > In message: <20040902000637.GA4120 at odin.ac.hmc.edu>
> >
> > Brooks Davis <brooks at one-eyed-alien.net> writes:
> > : - After 5.3 is released, declare that upgrades to 6.0 from
> > : releases other then 4.x (x>=11) and 5.y (y>=3) require special
> > : handling and allow if_data to grow as demand requires.
> >
> > There have long been plans to remove support to upgrade to 6.0 from
> > 4.x, and I plan on moving forward with those plans after the 5.3
> > branch. There are a large number of hacks in place to allow
> > upgrading all the way back to the 4.0 branch point, and these hacks
> > have been the source of a lot of frustration and gnashing of teeth
> > over the years. By right of conquest (eg writing the legacy
> > library and working with both sides of this issue for litterally
> > years), and by general consensus of the folks that do the grunt
> > work to make it possible to upgrade, I think that desupporting
> > upgrade to 6.0 from anything less than 5.2 (or maybe 5.1 for a
> > time) is a reasonable path to follow. Given that the rest of the
> > build system support for upgrades will be limited, I'm not sure the
> > benefit of supporting the upgrade from 4.11 to 6. We never really
> > supported upgrading from 3.5.1 to 5.0-Release, for example.
>
> Note that a change of the size of struct if_data doesn't totally
> break ugprades from old versions, it just requires a bit of
> pre-planning if your upgrade process requires ifconfig or if you need
> the ability to roll back.
Yes, thanks for the perspective reminder. As you say, this is a boot
issue, not a build issue. We normally "just deal with it" for this
sort of thing (ps, netstat, etc blowing up). But ifconfig is a bit
more sensitive than ps. ifconfig can easily stop your system booting
while ps is just cosmetic.
--
Peter Wemm - peter at wemm.org; peter at FreeBSD.org; peter at yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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