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Thread: Help with Reboot Analysis

  1. #1
    Join Date
    Jan 2005
    Posts
    1,008

    Help with Reboot Analysis

    I'm aware of "random" reboots occurring on 7.2.2 well documented at TCF, apparently tivo is preparing a 7.2.2b release to address this; I don't have that problem exactly but I've experienced a couple of reboots, occasionally when rewinding live TV. I have attached my kernel log after this happened last night. Anything jump out at anyone? I've been reading some threads on MIPS disassembly...a little OMH but I'm going for it, after all nothing ventured, nothing gained.

    epc : 00b02404 Tainted: P
    That seems significant; is that the program counter where the error occurred? What is the taint? Does this pretty much entail disassembling tivoapp and analyzing the register where the error occurs?

    Thanks in advance.
    ScanMan --> Just another Tivo hacker...
    Killhdinitrd SA S2 Monte S2 Unscramble Upgrade Tivo Software

  2. #2
    Join Date
    Aug 2004
    Posts
    4,075
    Quote Originally Posted by ScanMan
    I'm aware of "random" reboots occurring on 7.2.2 well documented at TCF, apparently tivo is preparing a 7.2.2b release to address this; I don't have that problem exactly but I've experienced a couple of reboots, occasionally when rewinding live TV. I have attached my kernel log after this happened last night. Anything jump out at anyone? I've been reading some threads on MIPS disassembly...a little OMH but I'm going for it, after all nothing ventured, nothing gained.


    That seems significant; is that the program counter where the error occurred? What is the taint? Does this pretty much entail disassembling tivoapp and analyzing the register where the error occurs?

    Thanks in advance.
    Here's an example of walking through debugging a tivoapp crash. The links at the bottom will help you fill your toolbox with the tools you'll need.

    In my experience, tivoapp crashes are nearly always the result of a bad patch. It's also possible that it is a hardware problem, for example, bad memory. My advice to you is to revert back to a stock tivoapp (md5sum for 7.2.2-oth.01-2 should be 839b41d7b3cbc353a04f4e8dc7fc7b56) to see if that crashes.

    Looking up the crash PC in the dissassembled tivoapp shows the crash site:
    Code:
    0x00b023f8 0x27bdffd8]addiu  sp,sp,-40
    0x00b023fc 0x00801821 move   v1,a0
    0x00b02400 0xafbf0024 sw     ra,36(sp)
    0x00b02404 0x9062003c lbu    v0,60(v1)
    The crash dump indicates it has an "illegal read" of address 0000003c. This doesn't make sense to me given the instruction stream above and your register dump. This makes me think your instruction stream was modified, either with a bad patch, or due to bad memory.

  3. #3
    Join Date
    Jan 2005
    Posts
    1,008
    Thanks for that link Jamie, I had bookmarked it already along with a couple of threads on mips disassembly and mips.dasm.pl. I should have mentioned I did Superpatch with 7.1's patch for 7.2.2-oth a few weeks ago, but it seems to be running fine except for a couple of these reboots when rewinding live TV. Oh, and another thing, I have an identical "240" same hacks, etc. which hasn't developed this glitch.
    Last edited by ScanMan; 04-25-2006 at 01:07 PM.
    ScanMan --> Just another Tivo hacker...
    Killhdinitrd SA S2 Monte S2 Unscramble Upgrade Tivo Software

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