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Re: RHEL and FC Kernels



On Sat, Apr 09, 2005 at 12:22:14AM -0400, William M. Quarles wrote:
 > Dave Jones wrote:
 > >On Fri, Apr 08, 2005 at 08:32:15PM +0100, Andy Hudson wrote:
 > > > Hi,
 > > > 
 > > > This may sound a bit naive, but what are the fundamental differences 
 > > > between an EL kernel and a fc3 kernel?
 > > > 
 > > > I'm expecting someone to say either RTFM or that EL kernels have 
 > > > specific patches applied to make them more stable than fc3, say.
 > <snip>
 > >
 > >Feature-wise, both streams have more-or-less the same added-Red Hat
 > >patches (Exec-shield etc).  RHEL has a 4g4g -hugemem kernel, but
 > >that's about the only difference.
 > >
 > >To give you something of an idea how much things diverge, here's
 > >the current number of patches included against various trees
 > >including some historic trees..
 > >
 > >RHL9:     174
 > >Fedora Core 1:     107
 > >Fedora Core 2:      80
 > >Fedora Core 3:      69
 > >Rawhide:      61
 > >RHEL4:     400
 > >
 > >Note that as we get newer releases of Fedora, the patchcount
 > >goes down.
 > 
 > OK, a couple of things don't make sense.
 > 
 > If "both streams have more-or-less the same added-Red Hat
 > patches," why are there over five times as many patches in RHEL 4 than 
 > in FC3?

Because RHEL4 is 2.6.9 + backports of fixes from 2.6.10 & 2.6.11
FC3 is 2.6.11.  The 2.6.9 FC3 kernels were 99% 1:1 with RHEL4 kernels
except for the config options used (RHEL4 doesnt enable as many modules
as FC3 does for various reasons).

 > Also, is there an explanation for why the patch count keeps 
 > going down as newer versions of Fedora Core are released?

- The real important bits get backported from the -rc release in progress.
  Thus, when a rebase happens when that -rc turns into a new upstream
  release, they get dropped as they're now included in the tarball.

- Where it makes sense, we push the patches from our tree upstream asap,
  so they end up in the next upstream release, and hence also get dropped
  from our local tree.

- As upstream changes, sometimes it becomes easier/cleaner/unnecessary to do some things.

- Sometimes things get cleaned up in the newer releases, that take a while
  to propagate back to the earlier releases.
  The restricted /dev/mem patch for example was 4 patches in FC2/RHEL4.
  It's 2-3 in FC3/FC4

		Dave


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