Re: [BUG] Alpha (EV56), lseek64, and /dev/kmem

[Måns Rullgård]

Kelledin <kelledin+LKML@xxxxxxxxxxxxxxxxxxx> writes:

> I just found that on my Alpha box, lseek64() has a bit of 
> difficulty seeking through /dev/kmem to extremely high 
> values--specifically, any value >=0x8000000000000000 (the 64th 
> bit set).  Whenever it's supposed to seek to (and return) such a 
> value, lseek64() returns -1 instead and sets errno to a 
> seemingly random garbage value.  Userspace has no real choice 
> except to interpret this as an error.
>
> So far it's doing this on both xfs and ext2/3, so I'm betting 

/dev/kmem hasn't anything to do with filesystems, right?

> it's fs-independent.  I suppose it could be the kmem driver 
> itself deciding to be quirky?  I have no way of knowing if 
> lseek64() will stumble like this on a real file, as I'd probably 
> need more drive space than God to test that!

You could create a sparse file, but I don't think any filesystem
support that big files.

-- 
Måns Rullgård
mru@xxxxxxxxxxxx

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