Re: UFS not 64-bit clean?
Re: UFS not 64-bit clean?
- Subject: Re: UFS not 64-bit clean?
- From: Chris Bednar <email@hidden>
- Date: Tue, 11 Dec 2001 16:19:53 -0600 (CST)
>
> I went through all this with Linux back when I had time
>
> to fool with things like arch/ppc/kernel/misc.S, but I'm hoping
>
> to keep myself kinda clueless about building xnu as long as
>
> I can ;)
>
>
As with all of the widely available source code bases for kernels I have
>
seen, it is not that bad to build, but it requires specific steps (some
>
of which may or may not be well documented).
Yup. Building, installing, keeping different versions on
the same system, making sure modules are installed right...
just not ready for the learning curve today. I'll try it
after I get a good run of sleep.
>
> like `rsh zorak cat RedHat7.2.iso > RedHat7.2.iso` and
>
> it ran without complaint, but the file looked to be truncated
>
> at 4G.
>
>
This is not about 64bit cleanliness (that really involves in memory
>
structure and call alignment). The max file size on UFS is either 2 or 4
>
gigs.
Really? Any UFS, or just Darwin's? All of this worked in
FreeBSD. Am I confused, or is this really because the UFS
code in Darwin is from the dim, ancient past?
>
Um, if you really want to try to build LFS you can be adding the line
>
"option LFS" to the conf files in xnu. You really do not want to though.
You are correct. I'm having a language problem; I mean
``Large File Summit''; all I mean by LFS is that file offsets are
64-bit, and I can have files bigger than 4G.
The reason I used the expression ``64-bit clean'' is that
I assumed that the situation was like that with pre-2.4 linux;
on-disk structures were 64-bit, but the kernel code wasn't.
I do see (xnu-9-1/bsd/ufs/ffs/ffs_vfsops.c:390, for example)
that there's a check to see if the on-disk maxfilesize is greater
than 4GB (in which case it's reset in memory to 4GB), and that
on-disk number does appear to be 64 bits wide, as is, I think,
the on-disk i_size...
----
Chris J. Bednar
Director, Distributed Computing Product Group
http://AdvancedDataSolutions.com/