On Wed, 5 Jun 2019, Andrea Vai wrote: > Hi, > Il giorno mer, 05/06/2019 alle 10.26 -0400, Alan Stern ha scritto: > > On Wed, 5 Jun 2019, Andrea Vai wrote: > > > > > Hi, > > > Il giorno mar, 04/06/2019 alle 07.43 +0200, Greg KH ha scritto: > > > > On Mon, Jun 03, 2019 at 01:13:48PM +0200, Andrea Vai wrote: > > > > > Il giorno gio, 30/05/2019 alle 06.25 -0700, Greg KH ha > > scritto: > > > > > > [...] > > > > > Hi, > > > > > > > > > > > Any chance you can use 'git bisect' to find the offending > > > > commit? > > > > > Yes, I am doing it as I managed to build the kernel from > > source > > > > > > > > Great! What did you find? > > > > > > # first bad commit: [534903d60376b4989b76ec445630aa10f2bc3043] > > > drm/atomic: Use explicit old crtc state in > > > drm_atomic_add_affected_planes() > > > > > > By the way, as I am not expert, is there a way to double-check > > that I > > > bisected correctly? (such as, e.g., test with the version before > > this > > > one, and then with this commit applied?) > > > > That is exactly the way to do it: Build a kernel from that commit > > and > > see that it fails, then revert the commit and see that the > > resulting > > kernel succeeds. > > > > (Note: The notion of "version before" doesn't have a firm meaning > > in > > the kernel, because some commits have multiple parents. The best > > way > > to see if a single commit caused a change is to do what I said > > above: > > revert the commit and see what happens.) > ok, thank you for pointing it out. So, my question is: how to revert a > commit? (sorry, I prefer to ask you because I am afraid I could do > something wrong, and don't trust too much myself and what I pick up > searching on the web. In the special case, I found "git revert", but > for example how could I revert back a "reversion"? :-/ (I know I miss > the basis, I never worked with git, so sorry for the stupid > question)). In this case it's very simple, since the 534903d60376 commit does have a single parent. You can just do "git checkout 534903d60376^". More generally, you could do "git show 534903d60376 | git apply -R -". That would tell git to write out the commit in the form of a patch and then apply the patch in reverse. Alan Stern > > Incidentally, it seems very unlikely that a commit for the drm > > subsystem would have any effect on the behavior of a USB storage > > device. > > well, I had the same doubt and that's the reason I was trying to do > the check: I'm afraid I have done something wrong or made a mess with > the bisect process. > > Thank you, > Andrea
