Re: large file support? (fwd)

Alan Cox (alan@lxorguk.ukuu.org.uk)
Sun, 17 Aug 1997 13:46:13 +0100 (BST)


> functions/syscalls if the file is smaller than 2GB. If the descriptor
> is used with a syscall for small files and the file is larger than 2GB
> the operation should fail and return EOVERFLOW.
>
> I've talked a bit with Alan about this so he might be a good person to
> talk to before starting this (especially since he's sceptical). I can
> only say that once the kernel has this stuff the libc will follow a
> few days later.

There are several reasons I'm sceptical. Firstly a 64bit aware bash opens
a file redirection to a 32bit app which then blows up mysteriously...

The "file smaller than 2Gb" is unenforcable because other processors
may also be altering an object, this object might also change remotely
on a networked fs.

Obviously certain operations should fail - an lseek(), any attempt to
go past 2^31 bits on an fs that isnt 64bit aware (again this is hard
as two people may be writing). An mmap() of a small chunk that overlaps
2^32 is possibly a nasty one to handle but its just a "catch all cases"
thing.

The big problem is the EOVERFLOW blowing up apps it doesnt need to