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Author Topic: Write "verbose messages" not to screen, but to file?  (Read 7236 times)

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Voltaire

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Write "verbose messages" not to screen, but to file?
« on: May 19, 2011, 01:08:13 PM »
Hi Folks, I have the problem here that system starts up to a certain point - and then stops with a black screen. Even in verbose mode (-v) it is not visible up to where the system is starting up an at which point it is stopping.

Question: is there a possibility to "write the verbose messages" into a file that can be looked at later? I did not find anything about writing verbose-info into file in the manual.

I have "dual boot" and can boot into other partition, from where to access the problematic boot-up-drive is no problem.

Thanks for info about it.

Blackosx

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Re: Write "verbose messages" not to screen, but to file?
« Reply #1 on: May 19, 2011, 03:10:32 PM »
Hi Voltaire

Chameleon does record a boot log to OS X's registry for viewing, but I guess that's only useful once OS X is booted.
Does your system stop before or after the boot process is handed to the OS X kernel?

Also, what manual are you referring to?
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Voltaire

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Re: Write "verbose messages" not to screen, but to file?
« Reply #2 on: May 20, 2011, 12:52:09 AM »
Just to clarify - please correct me if I am wrong:

with chameleon I have the possibility to a) select the boot partition, and b) eventually set some boot-parameters like -v (for verbose) or -x (for save-mode / "without kexts").

This runs so far with no problem - and I can let the OS boot. So as you write, in my case the system stops after boot process is handed to OS X kernel.

The problem is that I cannot see the verbose messages as they pass too fast and are not visible anymore at a certain point (at stop).

Now I would like not to display the verbose-messages to the screen, but to write them into a file that I can read fromt the other still bootable partitoin.

As verbose or safe-mode is started by chameleon-parameter, I am supposing that in the same way there would be some kind of option-setting to make verbose-messages not to display to screen, but to write them to file. I don't know if that is the case.

So I was referring to chameleon-manual ("official chameleon docs") where I did not find anything about that.

Hope you understand now.

Or is there some other way for reading the boot log?
« Last Edit: May 20, 2011, 01:56:24 AM by Voltaire »

Gringo Vermelho

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Re: Write "verbose messages" not to screen, but to file?
« Reply #3 on: May 20, 2011, 04:45:40 AM »
No switch is needed, once Chameleon is done, what you see when booting verbose is being written to a file each time you boot.
This is not mentioned in the Chameleon docs because at that point the boot process has been handed over to the OS and you would look at the boot logs the same way you would look at them on a real Mac.

Look for kernel.log and system.log in /private/var/log.
On a working system you can run Console.app and browse all the system logs.

If you want to see what Chameleon is doing while it's preparing to boot OS X, add wait=y to /Extra/com.apple.Boot.plist.
On a working system, you can copy bdmesg (built when you compile Chameleon 2.0 RC5) to /usr/bin and then run it from terminal once OS X is running. This will provide the same output as wait=y.

As we discussed earlier, booting with -x does not mean that you are booting "without kexts". Booting with -x is the same thing as holding down the shift key when booting OS X on a real Mac. That is the reason why it's not documented here - Apple does a great job with that already: http://support.apple.com/kb/ht1564
« Last Edit: May 20, 2011, 06:00:04 AM by Gringo Vermelho »
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Blackosx

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Re: Write "verbose messages" not to screen, but to file?
« Reply #4 on: May 20, 2011, 08:13:41 AM »
Voltaire - There's not much else for me to say here as Gringo has kindly answered all your questions. (Thanks Gringo :))

One extra thing to note on the problem you describe with the OS X kernel verbose message scrolling too fast to read is also true for owners of real Macs (as far as I'm aware). But in most cases where the kernel stops the boot process due to error, the cause is shown in the last few lines of text, or maybe sometimes the last 10 or so lines.
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Voltaire

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Re: Write "verbose messages" not to screen, but to file?
« Reply #5 on: May 20, 2011, 12:10:30 PM »
Voltaire - There's not much else for me to say here as Gringo has kindly answered all your questions. (Thanks Gringo :))
Thanks - that really clarifies the situation here ... hope that I'll find out what happens at bootup. The affected system is not working, so I have to go to look there from a working system on a different bootup-partition from wich I have access to the affected one.

One extra thing to note on the problem you describe with the OS X kernel verbose message scrolling too fast to read is also true for owners of real Macs (as far as I'm aware). But in most cases where the kernel stops the boot process due to error, the cause is shown in the last few lines of text, or maybe sometimes the last 10 or so lines.
Additional problem is that screen just gets black ... I tried to record a video with video-mode of photo-camera - but isn't readable neither ... I'll have a look at the logfiles.