On Wed, Feb 07, 2018 at 06:37:06AM -0800, Greg Kroah-Hartman wrote: > On Tue, Feb 06, 2018 at 06:48:17AM -0800, Guenter Roeck wrote: > > On 02/06/2018 05:14 AM, Greg Kroah-Hartman wrote: > > > Thanks for letting me know, that's great to hear as I just had a > > > question from some companies who are worried that taking stable patches > > > will cause tons of merge issues. It hasn't in my experience, and seeing > > > reports of this from others is great news. > > > > > > > From merging v4.4 and v4.14 into the respective ChromeOS branches, I would conclude > > that merging is for the most part easy. Major source of conflicts, if they happen, > > is that we may already have picked up additional commits from upstream. > > > > This is only true, though, if merges are done on a release-by-release basis > > and if the merge happens shortly after a stable release is available. Otherwise, > > as time goes by, merges become more and more difficult (almost exponentially > > over time). Wait for more than 2-3 months between merges and it becomes almost > > impossible. > > > > For reference, the top of tree for both branches is > > v4.14.16-3823-g597d36f1d331 > > v4.4.114-12977-ga207b53fe939 > > Ugh, 12k patches is not trivial, gotta love those graphic drivers :( > That, plus a gazillion backports, plus vendor specific out-of-tree wireless drivers, plus all the Android stuff. No, there is no "love" involved, only annoyance :-(. > > meaning there are _lots_ of patches on top of the mainline stable releases. > > > > Also, overall, the rate of regressions is quite low (if I recall correctly, > > somewhere between 3 and 5 in chromeos-4.4, and one so far in chromeos-4.14, > > ie below 0.1%). > > Thanks a lot for the feedback, this helps out a lot when talking to > companies that are "afraid" of doing merges with stable. > > Based on this, one phone vendor just forward merged their 4.4.y based > tree to the latest release in a few hours with no reported problems at > all, so it has already helped out with tangable results. > Excellent. More test coverage! Guenter