Re: Problem with fcntl/F_LOG2PHYS (was: Re: How to read files from disk directly?)
Re: Problem with fcntl/F_LOG2PHYS (was: Re: How to read files from disk directly?)
- Subject: Re: Problem with fcntl/F_LOG2PHYS (was: Re: How to read files from disk directly?)
- From: Stanley Sieler <email@hidden>
- Date: Wed, 06 Jul 2011 22:36:05 -0700
Re:
On Jul 6, 2011, at 20:00 , Ken Hornstein wrote:
>> Has anyone successfully used fcntl/F_LOG2PHYS?
>> Or, can anyone shed light on why I should be getting this kind of result?
>
> There was some discussion about the limitations of F_LOG2PHYS. Some things
> mentioned involved filesystem compression; if you look at hfs_vnop_blockmap(),
Interesting...I hadn't thought about that. I'll check tomorrow, thanks.
> you can see that you get ENOTSUP if the file is compressed (looks like
> you need to do some magic to make that happen).
>
Although I didn't specifically mention it, I check functional results / errno all the time :)
I.e., I did not get any errors.
>
> Maybe there's some interoperability between F_LOG2PHYS and crazy-ass
> virtual currency? :-) But seriously ... it's possible they've been
> hfs+ compressed (download hfsdebug to check).
>
:)
Now that I think about it, the vmem file and the size db files are probably open for some kind
of access at this time (because VMWare is running, as is the Bitcoin computation demon)
... still, there's no question in my mind this is probably a bug. The question is: in fcntl or in the documentation?
> What does work is two-machine debugging with gdb. I do that all of the
> time and it works great.
I'll try to try that out sometime...sounds like fun!
thanks,
Stan
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