Re: bisect gives strange answer

From: Sanjoy Mahajan <sanjoy@mrao.cam.ac.uk>
Date: Aug 4, 2005, 17:41 UTC
Message-ID: <E1E0jiv-0003c4-00@skye.ra.phy.cam.ac.uk>
In-Reply-To: <20050804172635.GA14144@kroah.com>

> By any chance, is this patch causing you problems?

No, sadly. But I had hopes! As I think about it more, there's no way it could, since I have CONFIG_HOTPLUG=y, so moving the CONFIG_HOTPLUG would not change anything (for those who don't know the patch, it is appended below).

My latest theory is that I fed bisect incorrect good/bad data. Perhaps If I had checked out and compiled those intermediate versions from scratch, each version in a separate directory, then I would have got different answers. Two possible reasons:

1. The kernel Makefiles ar do not understand every subtle dependency.
   So they might get confused by updating to different tree states (as
   the bisect progresses) because those updates change Makefiles and
   include files.  In other words, I should have done 'make clean' or
   'make mrproper' before each kernel compile.

2. git-bisect-script doesn't use -f when it does 'git checkout', so
   files that should be updated are not.  Right now I'm in the middle
   of recollecting the data with git-bisect-script using -f in all
   uses of git checkout (unless that is a really silly idea).

-Sanjoy

git diff a18bcb7450840f07a772..3d3c2ae1101c1f2dff7e2f9d514769779dbd2737

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -17,13 +17,13 @@
  * Dynamic device IDs are disabled for !CONFIG_HOTPLUG
  */
 
-#ifdef CONFIG_HOTPLUG
-
 struct pci_dynid {
	struct list_head node;
	struct pci_device_id id;
 };
 
+#ifdef CONFIG_HOTPLUG
+
 /**
  * store_new_id
  *