Loopback filesystems in a file on vfat.

[0x0065]

TWIMC.

on your NoDo list, you list alternative filesystems.
I appreciate your reasons for choosing not to support this. 

In addition to listing partitioning the device as a work around on the NoDo list, perhaps consider mentioning loopback filesystems.

If the issue is just preserving file attributes that fat doesn't support, then with a loopback filesystem you can use whatever filesystem you like. I don't really know or care whether MS can support them, but on a complete OS, it allows you to (maybe temporarily) make a disk image in a file on the player, and mount it like a disk. You could even use strong crypto if need be. http://tldp.org/HOWTO/html_single/Cryptoloop-HOWTO/#loopdevice-setup

Sitting it on a vfat filesystem, you'd obviously loose any other benefits of a more sophisticated file system, but seriously we're talking about writing to a music player... Doing it on a flash based disk could be bad. I don't know. Probably depends on how it's done. Journaling filesystems are apparently really bad for flash disks because they write a lot of little bits of data all the time. Apparently they're broken for loopback in some cirtumstances anyway.

just a thought.

[Llorean]

Please follow our forum guidelines. I have no idea whatsoever what "TWIMC" means, and we ask that you attempt to use real words, and restrict yourself to the abbreviations in the project glossary.

[saratoga]

If the issue is just preserving file attributes that fat doesn't support, then with a loopback filesystem you can use whatever filesystem you like. I don't really know or care whether MS can support them, but on a complete OS, it allows you to (maybe temporarily) make a disk image in a file on the player, and mount it like a disk. You could even use strong crypto if need be. http://tldp.org/HOWTO/html_single/Cryptoloop-HOWTO/#loopdevice-setup

Can you think of any real use for this on a DAP?

[Llorean]

I *think* he's just referring to people who may want to use their DAP also as an external HD. So, not something that would be used except when attached to a host PC.

[GodEater]

TWIMC = To Whom It May Concern

[0x0065]

Can you think of any real use for this on a DAP?

• transferring files from one 'real' operating system to another without loosing file permissions, attributes & other meta data.
• if you have to transport 'commercial in confidence' files either into or out of the US of A (given the crazy warrantless search rules recently upheld at US airports, and assuming that you intend to meet your legal obligation to protect the data) can you think of another place where an encrypted binary blob would be more likely to fit in with the crowd?

Please follow our forum guidelines. I have no idea whatsoever what "TWIMC" means, and we ask that you attempt to use real words, and restrict yourself to the abbreviations in the project glossary.

RE: TWIMC = To Whom It May Concern...
RE = with regard to / further to
FYI:  US of A = United States of America... (in case you were wondering)...
FYI = For Your Information. (i.e. you aren't expected to 'action' anything)
i.e. = id est = that is = that is to say / in other words

[saratoga]

Can you think of any real use for this on a DAP?

• transferring files from one 'real' operating system to another without loosing file permissions, attributes & other meta data.
• if you have to transport 'commercial in confidence' files either into or out of the US of A (given the crazy warrantless search rules recently upheld at US airports, and assuming that you intend to meet your legal obligation to protect the data) can you think of another place where an encrypted binary blob would be more likely to fit in with the crowd?

Neither of those are uses for a DAP.

[dan_a]

Surely there would be no need to implement any of that in Rockbox - you simply use the DAP as an external hard drive on an operating system which supports loopback file systems.

In fact, in the example you give of wanting to transport sensitive information, having the DAP able to natively read the loopback file system would take away the protection that the otherwise hidden files had.

[0x0065]

Surely there would be no need to implement any of that in Rockbox - you simply use the DAP as an external hard drive on an operating system which supports loopback file systems. In fact, in the example you give of wanting to transport sensitive information, having the DAP able to natively read the loopback file system would take away the protection that the otherwise hidden files had.

on your NoDo list, you list alternative filesystems.  I appreciate your reasons for choosing not to support this. 
In addition to listing partitioning the device as a work around on the NoDo list, perhaps consider mentioning loopback filesystems.

dan_a

Since you clearly understand my initial post, What do you think about adding it as a suggested work around on your NoDo list?

Please advise

Thanks & regards

e

p.s. in case this is STILL not clear to anyone, I'm proposing a change to the website.
p.p.s. I am not proposing a change to Rockbox.
p.p.p.s. I've already done this on my X5. I've provided a link to a suitable manual. (Llorean please note my restraint here :-)

[JdGordon]

I cant see what this has got to do with rockbox.. but anyway, the NoDo is on a wiki, if you want to add it, please do.
BUT, its not a work around for the other filesystems nodo point. the point there is rockbox wont be made to support reading from other filesystems (the big one if HFS+ for mac formatted ipods, or ext2/3 for linux boxes). we dont care about your data secutiry, do what you want with other files on the DAP...

and anyway, storing a loopback FS on a fat32 formatted disk is pretty silly... max 4gb storage, and anyone smart enough will know how to read it anyway

[0x0065]

I cant see what this has got to do with rockbox.. but anyway, the NoDo is on a wiki, if you want to add it, please do.

Hmmm. Thanks for the invitation. Some people on these things get really obnoxious & confrontational with new people contributing anything. I wouldn't want to offend anyone.

BUT, its not a work around for the other filesystems nodo point.

It's as much of a work around as partitioning the device. It's also temporary & doesn't involve messing with the partition table. I'd imagine at least some of these devices are a little sensitive about people shuffling their partitions around.

and anyway, storing a loopback FS on a fat32 formatted disk is pretty silly... max 4gb storage

the 4gb limit is only one of vfat's numerous and manifold limitations. I've clearly stated that it's only a work around to a clear subset of vfat's limitations. I might be silly but at least I can read. FYI: HFS+ is a journalling filesystem. Rumour has it that it's largely based on reiserfs. If this is true, the journalling is probably fairly integral, & not optional as in ext2/3. Refer my earlier comment on journalling filesystems on flash disks & loopback devices.

anyone smart enough will know how to read it anyway

yeah! If given a multi-million dollar, top 500 supercomputer or a couple of months/years of compute time...
...for the record, if anyone possessing such a thing is that 'motivated', I'll let you read anything, on the condition that you ask nicely

HFS+ = Hierarchical Filing System (improved)
VFAT = Virtual File Allocation Table
ext2/3 = extended [file system] version 2 or 3
FYI in this case means "I've no obligation to tell you, given that you're not paying me for such a service, but I feel morally obliged to inform you that"

p.s. clearly if you cared about people's data security, you'd support a less flaky filesystem. I don't see why you feel the need to explain your feelings on this so explicitly & publicly.

[gevaerts]

What's wrong with tar or cpio ? Why do you want to use a loopback device for something like this ?

[AlexP]

p.s. clearly if you cared about people's data security, you'd support a less flaky filesystem.

What we care about is compatibility with all operating systems (FAT32 just works on Windows/Linux/whatever) whilst not making the firmware of an embedded device that is designed to play music and not to transport sensitive information unnecessarily complicated by supporting other filesystems for no real gain in terms of the primary function of the device, when FAT32 is perfectly good for the job of a DAP.

[0x0065]

fg

That's a really perceptive and valid comment expressed quite politely. Thank you.
I'm sure a tar file would cover a lot of cases.

• I assume the people repeatedly asking you for ext2/3 & hfs+ support want it as a 'work in progress' file storage system.
• I've never heard of someone booting off a tar file... (^_<) ...have you? especially not a read/write root partition.
• Can you mount a tar file transparently into a file system? never tried.
• by the time you mix strong crypto with uncompressing to a disk for editing, and start considering the kind of tidy up work you'd have to do, a loopback filesystem starts to look less complicated, once you know how.

AGAIN, just a suggestion. Perhaps not for everyone. May be an answer for some of the people you've elected not to support.

FAT32 is perfectly good for the job of a DAP.

Apologies BigBambi. That was more a dig at jdgordon's tone. Not RockBox as a project, which I quite enjoy daily. For the record:

just a thought.

we ask that you attempt to use real words

Can you think of any real use for this on a DAP?

(clearly people are asking for equivalent functionality)

Neither of those are uses for a DAP.

(Actually I'm using a 'DAP' for exactly that at this very moment.)

we dont care about your data secutiry, do what you want with other files on the DAP... and anyway, storing a loopback FS on a fat32 formatted disk is pretty silly...

might want to look at a policy on patronising & belittling newcomers without even bothering to read or understand their posts...

[soap]

I will lock (if not delete) this thread if it degrades into insults and attacks.  This subject is barely related to Rockbox as is - and as far as I can tell (willing to be corrected) the Rockbox side of this subject has now been addressed. 
The wiki is available for editing...


P.S. - saratoga is 100% correct when he says this (transporting data securely) is not the role of a DAP.  It is the role of a portable drive.  It has nothing to do with playing music (or videos).  Rockbox is a DAP firmware - its primary focus is and will always be to play media files.  You are using your DAP as a portable drive - that is fine - but I find the expectation that the DAP firmware be extended into non-DAP roles confusing.