[ros-general] IFS-faq v0.9

Sat Feb 28 15:19:42 UTC 2004

Hi Robert

I've added your FAQ to the slightly reorganized developer site (FAQs 
have their own pages depending on functional area):
http://reactos.com/reactos_developer_site/faqs

Cheers
Jason

Robert Köpferl wrote:

> I finished a new version of the FAQ.
>
> I think it's good enough to be put on the website.
> Can someone do this?
> Is there some format that has to be used for ezpublish?
>
> Eric Kohl schrieb:
>
>> "Robert Köpferl" <rob at koepferl.de> wrote:
>>
>>
>>
>>> So is iso9660 available?
>>
>>
>> Yes!
>>
>>
>>> VFAT = long name extension?
>>
>>
>> Yes!
>>
>>
>>> UDF?
>>
>>
>> The filesystem recognizer driver fs_rec.sys recognizes UDF file 
>> systems but
>> we don't have a filesystem driver yet.
>>
>>
>> Regards,
>> Eric
>>
>> _______________________________________________
>> ros-general mailing list
>> ros-general at reactos.com
>> http://reactos.com/mailman/listinfo/ros-general
>
>------------------------------------------------------------------------
>
>
>
>
>  ROS-Filesystem FAQ
>
>ReactOS uses file system drivers as WinNT does. For that reason it
implements 
>the IFS-interface which stands for Installable File System.
Therefore it is or 
>will be able to load and use IFS-drivers. The same as WinNT and
WinXP also uses. 
>At the time of writing ReactOS was still unable to load WinNT-native

>IFS-drivers. But some time, ROS will be able to load even native
NTFS-drivers.
>
>
>      Q: Can we impliment the FreeDos version of the FAT32
filesystem?
>
>A: Reactos supports Fat32 for ages. There's no need to implement
another one.
>
>
>      Q: Does ReactOS support VFAT and long names?
>
>A: What are short names? OK. ROS natively supports long and unicode
filenames. 
>So it's up to the file system driver how it deals with it. The
FAT-driver 
>delivered with ReactOS supports VFAT (=long names on FAT).
>
>
>      Q: Why don't you implement ext2/3 but messing around with
NTFS?
>
>A: Because NTFS is a major feature which must be supportet at some
time. Ext2/3 
>is of course a topic for us, however there exist already projects
whose goal it 
>is to implement Ext2/3 for NT. We will utilize these drivers when
they got good 
>enough.
>
>
>      Q: Where can I find the Ext2/3-IFS for NT?
>
>You can find it here:
>http://uranus.it.swin.edu.au/~jn/linux/ext2ifs.htm, 
>http://sys.xiloo.com/projects/projects.htm#ext2fsd and 
>http://ashedel.chat.ru/ext2fsnt/
>
>
>      Q: Can I help programming installable file system drivers?
>
>A: Yes, there's lots of work to do around IFS-drivers. It's however
very hard to 
>program. I like to say that programming dirvers is hard but
programming file 
>system dirvers is the king's discipline. If you are a real kernel
hacker, come 
>to our maling list and anounce yourself.
>
>
>      Q: Can we use ext2/3 instead of poking around in NTFS
>
>A: Yes, it's up to you, which file system you want to use. For now
however 
>neither the ext2/3-IFS nor the our NTFS-IFS is ready to use for read
and write. 
>So there's still lots of work to do and so the only option is the
FAT-IFS.
>
>
>      Q: Why do you not make use of the Linux-NTFS project's
sources?
>
>A: These sources are rather ok, but as all NFTS implementations (but
the one 
>from MS) it lacks writing support. And there are still big areas of
NTFS wich 
>are undocumented/unknown. We are working together with them or just
using their 
>code. In the moment ther's however not that priority for NTFS. So
it's still 
>sleeping.
>
>
>      Q: I would vote for reiserfs as the standard FS for ReacOS
>
>A: Good Idea. However there's no ReiserFS driver for NT/ROS
available. You are 
>welcome to program one. I think in the last time there apeared one
in the net.
>
>
>      Q: How critical is NTFS support is for ReactOS to be
successful?
>
>A: ReactOS will eventually want NTFS support, but for now, there is
no critical 
>reason to have it. NTFS is primarily a hard disk filesystem, so the
only reason 
>one would absolutely need it would be if you wanted to access an
NTFS-formatted 
>physical partition on a hard disk installed in a ReactOS computer.
>Other file systems will be able to provide the advanced features of
NTFS 
>(journaling, ACLs, compression, hard links, etc.) if strict NTFS
compatibility 
>is not a requirement. All software comes on CD or DVD media
(ISO-9660 or UDFS), 
>or possibly on floppies (FAT). External media (compact flash, memory
sticks, 
>etc.) tend to be formatted FAT.
>
>
>      Q: The JFS-sources (also for OS/2) are free to download. Why
not make JFS
>      the standard FS in ROS?
>
>A: Yes, at least an IFS is already planned. Since JFS is still a
state of the 
>art file system with journalling, big file+partition sizes ACLs and
extended 
>attributes and hard links, it would well suite ROS. We are working
on it but you 
>are welcome to help.
>
>
>      Q: How do you deal with case sesitivity (i.e. ext2) ?
>
>A: Case sensitivity is not a problem of the file system itself. It's
an aspect 
>of the corresponding dirver. The object manager which provides the
whole 
>namespace supports case sensitivity natively. So IFS-drivers get a
special case 
>flag which they must handle accordingly. A ported file system
diriver must 
>therefore be able to handle both, case (in)sensitivity.
>
>
>      Q: Does a 64-bit file system run on a 32-bit machine?
>
>A: Yes. The 64-bit are just the adressing on the disk. It has
nothing to do with 
>the executable which contains the driver. That executable hat that
manny bits as 
>the whole operating system has.
>
>
>      Q: What file systems does ReactOS support, now?
>
>A: For now, the only file system supported is FAT(12/16/32) without
VFAT.
>
>
>      Q: What file systems will ReactOS support?
>
>A: Our goal is to support as many file systems as possible. There
can be 
>developed IFS-drivers for at least these disk file systems which are
available 
>with linux. It's however verry hard to program a compliant/working
file system 
>driver. So it will take some time.
>At least there will be:
>
>    * FAT(12/16/32) plus VFAT
>    * ISO-9660 - CD-ROM
>    * one Higher FS like ext3, NTFS or JFS
>    * NPFS - named pipe file system (internal FS)
>    * MSFS - mailslot file system (internal FS)
>
>
>      Q: I have an idea: Why not throw away these odd drive letters?
>
>A: Old Idea. I'd say that also MS has had this idea. But they didn't
realize it 
>up to now. Why? In the ROS-team there are also thinkings about this
issue. But 
>up to now there has not been a sufficient conclusion about this
topic. Maybe MS 
>is also still thinking.
>There are Ideas as having a memory based mount file system or
uncovering the 
>object managers name space to win32-apps or drive words. Everything
brings 
>disadvantages with it.
>By the way: The ROS/NT-Kernel doesn't work with drive letters. These
are a 
>relict of DOS (or should I say CP/M) in win32.
>
>
>      Q: What is a Redirector?
>
>A: This is a special form of an IFS driver. It doesn't implement a
on disk file 
>system. Instead it relies on the kernel's network stack and provides
most times 
>a remote file system (i.e. SMB-Shares).
>
>
>      Q: What is a file system recognizer?
>
>A: A real file system driver is a heavy wight. Loading it just for
it to see 
>that there is no partition it could mount is waste. For this reason
Dave 
>invented so called recognizer driver. They are more less integral
part of the 
>driver architecture. Such a little driver gets loaded and searches
partitions 
>for file systems it's companion IFS is capable of. If it finds such
a partition 
>it loads it's companion IFS to mount it.
>
>--------------------------------------------------------------------------------
>
>*SEH-Problem*: Structured exception handling (SEH) is used in
programming 
>ReactOS as it is used in programming for OS/2 or WinNT, too. SEH is
a game wich 
>is played between OS and Compiler (Keywords: __try, __except,
__finally). 
>ReactOS itself is SEH-aware and provides the infrastructure, however
up to now, 
>the used GNU-compiler is not capable of generating SEH aware code.
So one can't 
>compile a driver or program which uses SEH with the GNU-Compiler.
>
>© 2/2004 Robert Köpferl <>
>
>  
>
>------------------------------------------------------------------------
>
>_______________________________________________
>ros-general mailing list
>ros-general at reactos.com
>http://reactos.com/mailman/listinfo/ros-general
>

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