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 17:55:28 -0600 (CST)
On Tue, 11 Dec 2001, Umesh Vaishampayan wrote:
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On Tuesday, December 11, 2001, at 10:31 AM, Chris Bednar wrote:
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>
> I'm fooling with using UFS, and I notice that
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> I get in trouble at the 4-gig limit.
>
>
That's artificial limitation put in UFS few years ago when I implemented
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UBC. At that time the VM did not support 64 bit data paths. Hence anything
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above 4GB was not accessible. [Well, you could try to access it, but the
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offset would wrap and lead to interesting :-) data corruption]. Hence the
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following code was added:
Thanks for the clear answer! (and thanks to Louis for his,
too) I feel better and better about this OS... I might even try
building a kernel.
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bsd/ufs/ffs/ffs_vfsops.c:
Yep, I had just found that.
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Now that VM supports 64 bit data paths, the code above can be removed.
But will it work... well, I went through this with Linux;
maybe I'll try it again.
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> Is the darwin
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> UFS implementation not 64-bit clean?
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>
Yes it is.
Well, it is, in the sense that it won't (necessarily) crash
if there's a file over 4GB on the platter, but truncating the
file size this way doesn't seem all that clean to me...
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> 3) LFS-ready
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>
That you do not get without doing LOTS of work on it first...
Oh, don't be silly! There are only 15,364 lines of code in
bsd/ufs/* , and that includes comments! how much work could it be ;)
----
Chris J. Bednar
Director, Distributed Computing Product Group
http://AdvancedDataSolutions.com/