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 Post subject: exFAT notes
PostPosted: Mon Aug 09, 2010 4:31 am 
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Some small notes for a to-be-written exFAT wiki page:

- exFAT uses 32-bit FAT entries.
- When a file in exFAT has it's "no-fat-entries" bit set, assume they'd all be consecutive.
- Block allocation bitmap is leading over the FAT.
- FAT is still used for what it did before.
- There's a boot area of 24 sectors containing two large boot blocks of 12 sectors each.
- There's usually only one FAT that's mostly unfilled (because of that no-fat-entries bit).

- Using this information within a place where Microsoft holds its patents on this stuff is probably illegal. I don't live in such a place so I have no problem with using this information. The only reason I'd like to support exFAT is for interoperability with a future video camera or photocamera.

There's an awesome reverse engineering by a forensic examiner to be found at
http://www.google.com/url?sa=t&source=w ... 6q_7CRkmuQ

Also found if you google for "exfat reverse engineer".


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 Post subject: Re: exFAT notes
PostPosted: Mon Aug 09, 2010 4:36 am 
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Using this information within a place where Microsoft holds its patents on this stuff is probably illegal. I don't live in such a place
No enforceable software patents on ZZ9 Plural Z Alpha ? Cool !

That is a serious reverse-engineering effort.

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 Post subject: Re: exFAT notes
PostPosted: Mon Aug 09, 2010 5:17 am 
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gerryg400 wrote:
No enforceable software patents on ZZ9 Plural Z Alpha ? Cool !


ZZ9 Plural Z alpha, planet Earth, country Netherlands that is. Just traceroute to the IP address, should tell you the route to our solar system. Or didn't we roll out universe-wide traceroute & long-latency pings yet?


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 Post subject: Re: exFAT notes
PostPosted: Mon Aug 09, 2010 4:14 pm 
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Only that non-staff doesn't have access to your IP :wink:

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 Post subject: Re: exFAT notes
PostPosted: Tue Mar 03, 2015 7:33 am 
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Looks like I'm the only one that does this for fun.

I've updated the page at http://wiki.osdev.org/ExFAT with some basic info which, together with assuming it's otherwise FAT32, should be enough to make a read-only driver. There are too many unknowns to read-write though, and I know there's a hashing function in there somewhere so I know that there's oppurtunity for actively messing it up so don't use this as write info.

Filesystem reverse-engineered from only publicly accessible data on a non-Microsoft computer without working exFAT driver, with only publicly available data.


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