Date: Sun, 01 Aug 2004 19:25:04 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: scottl@samsco.org Cc: phk@phk.freebsd.dk Subject: Re: PCI-Express support Message-ID: <20040801.192504.98673359.imp@bsdimp.com> In-Reply-To: <410D5F45.1060902@samsco.org> References: <61725.1091393254@critter.freebsd.dk> <410D5F45.1060902@samsco.org>
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In message: <410D5F45.1060902@samsco.org>
Scott Long <scottl@samsco.org> writes:
: Agreed, and I'm looking for things besides stability that are going to
: bite us in the near future. 6.0 likely won't happen for 12-months
: after 5.3 at an absolute minimum, and I don't want PCI-E support to
: turn into something like Cardbus is with 4.x vs 5.x.
A big part of why CardBus evolved the way it did was because it
depended on pci extensions that Mike Smith explicitly said he wasn't
going to back port. Later, it was because of the acpi support in
current that wasn't in stable (most modern laptops do not operate
correctly with cardbus cards if you don't use acpi). Since the
changes were extensive and all over the tree, it was hard to back
port. Also, there was much optimism about the possibility of a quick
5.0, which evolved the way we all know.
I think that we should learn from this history that we should be less
afraid to back port when there's a highly anticipated feature. We
should be as pessimistic as possible when guessing the date for 6.0
for the purposes of deciding if something should go into the tree.
Eg, if we think that we can do 6.0 on a certain date, we should add a
year or two to that when deciding to back port or not. Had we applied
that rule with the CardBus code, we'd have back ported things w/o
hesitation. In fact, there was a preliminary port to -stable at the
time we branched, and that just wasn't kept up to date. We started
doing major changes too quickly, which made it harder to back port.
Anyway, I just wanted to speak up from my perspective from CardBus.
Warner
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