[johnnym]

Ok, I'm through, though I don't believe 4fc402b61836e8a270d48f5516496cfbfe57776b (0541ad29664165bece2a7957d02a188f9bafb73b in real) is the real culprit. I mean, yeah it is in the network code so could have a play in the problem EDIT: and it intruced a bug for big endian machines according to the next change to the according file, but why should it specifically affect IP28 and no other machine, not even the Indy which uses the same NIC?

I rather believe this is the reason of the problem I mentioned earlier (hangs after NFS mounts) and that I also saw on the Octane but which was gone later on EDIT: my memory played my a trick here: the Octane didn't hang but took a long time according to my logs at around the NFS mounts (the solution - according to the commit dates - was to replay 85caa4b also for sgi with 1583f1e). Also newer commits identified as bad did not hang on the Indigo². I'll look into that on the weekend probably.

Code:

$ git bisect log
git bisect start
# bad: [0d58b8b8b5e0621f84efa993ee9ef47605603beb] drop the -beta
git bisect bad 0d58b8b8b5e0621f84efa993ee9ef47605603beb
# good: [5b7ece61fa1aa6c1348e9b8f2e7b0863e6ea20e7] close enough to release, we drop -beta
git bisect good 5b7ece61fa1aa6c1348e9b8f2e7b0863e6ea20e7
# good: [9f850877c8e5a89e6bfb255f1f7026c00bb7875e] vmm(4): reference count vm's and vcpu's
git bisect good 9f850877c8e5a89e6bfb255f1f7026c00bb7875e
# bad: [970cf9c09324fa9781be02dc122de675098fbf1d] Don't yet configure smmu(4) on Qualcomm SoCs as used on the Lenovo x13s as it is still not ready for runtime use and probably needs further quirks.
git bisect bad 970cf9c09324fa9781be02dc122de675098fbf1d
# good: [a7cdf5850edf952aab05a1d12a910add326a1f7c] Make test table based, extend it a little
git bisect good a7cdf5850edf952aab05a1d12a910add326a1f7c
# bad: [a39c18f28d16b1a61658f6ce07a74bc58176db30] strlen was in v6 libc (s5/perror.c) but not documented till v7 ok schwarze@
git bisect bad a39c18f28d16b1a61658f6ce07a74bc58176db30
# good: [17fc9e5b1d3178a8d65cacff7114b83163f14a02] The IPv4 reassembly code is MP safe, so we can run it in parallel. Note that ip_ours() runs with shared netlock, while ip_local() has exclusive netlock after queuing.  Move existing the code into function ip_fragcheck() and call it from ip_ours(). OK mvs@
git bisect good 17fc9e5b1d3178a8d65cacff7114b83163f14a02
# bad: [4fc402b61836e8a270d48f5516496cfbfe57776b] Checking the fragment flags of an incoming IP packet does not need the mutex for the fragment list.  Move this code before the critical section.  Use ISSET() to make clear which flags are checked. OK mvs@
git bisect bad 4fc402b61836e8a270d48f5516496cfbfe57776b
# good: [cd0dd8f18578e5b883f43aa8ea64d31710ca1159] Force disabling the use of delay slots. This is ugly but gets the compiler to produce 99+% correct code at all optimization levels, and can help people who would like to tinker a bit with the backend.
git bisect good cd0dd8f18578e5b883f43aa8ea64d31710ca1159
# good: [0e641b41fe54fcc8de2a3351ff974e0677060113] Remove bogus mtw_read_cfg.
git bisect good 0e641b41fe54fcc8de2a3351ff974e0677060113
# good: [5e24e96cb0c2a092c174a5e9f83d4cbadf271e3f] Zap prototypes for nonexistent nd6_setmtu() and in6_ifdel()
git bisect good 5e24e96cb0c2a092c174a5e9f83d4cbadf271e3f
# good: [e62afb52dea0a7b7d0c6c099652a54e60340a22d] Fix RFC number in comment
git bisect good e62afb52dea0a7b7d0c6c099652a54e60340a22d
# good: [61f35befa9a0619b3becea84efb445917c00389e] Add a second test to validate the tables in the library.
git bisect good 61f35befa9a0619b3becea84efb445917c00389e
# first bad commit: [4fc402b61836e8a270d48f5516496cfbfe57776b] Checking the fragment flags of an incoming IP packet does not need the mutex for the fragment list.  Move this code before the critical section.  Use ISSET() to make clear which flags are checked. OK mvs@

Each bisect step required the following steps for verification:

1. tar repo state - seconds
   
2. copy it over to the NFS server - about 1m
   
3. untar it on the Octane to a 15K SCSI disk from NFS - about 20m
   
4. compile it - about 28m
   
5. test it on Indigo² - under 5m
   

...so roughly 50 minutes per step.