Re: Support for >2Gig files on i386

Theodore Y. Ts'o (tytso@mit.edu)
Sun, 16 Aug 1998 18:55:33 -0400


Date: Sun, 16 Aug 1998 17:00:05 +0200
From: Pavel Machek <pavel@bug.ucw.cz>

> If someone who understands the kernel programming issues wants to try to
> tackle the >2GB file problem, I'd be happy to work with them. There's a
> cheat you can do which bypasses the generic file read/write routines

Ok, what about following idea: make kernel option

[ ] 64-bit VFS (this is going to make your kernel slow).

Would that be so hard? If not, this might be the way to go. It is
ugly, yes, but it might be the solution for 2.2.X. I see, we would
have to add xstat - like interface...

Doing a 64-bit VFS on a 32-bit platform in a way which doesn't make the
existing VFS code scary and ugly (which would thus cause Linus to reject
the patch on the spot), may be fairly tricky, actually.

Also, many people who want >2GB files might not be happy with the speed
tradeoff to get >2GB files. They might be more willing to live with the
restriction that you can't mmap or execute >2GB files. (Especially
since addresses will still be limited to 32-bits, so you wouldn't be
able to mmap the entire file into memory anyway.)

That's why I was suggesting an approach that bypasses the VFS and the
generic file read/write routines for files >2GB. It's almost certainly
easier to implement, and I suspect it will fit more people's needs.

- Ted

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