Message-ID: <20011119163455.11507.qmail@web14804.mail.yahoo.com>
Date: Mon, 19 Nov 2001 08:34:55 -0800 (PST)
From: Rock Gordon <rockgordon@yahoo.com>
Subject: Re: Executing binaries on new filesystem
To: Terje Eggestad <terje.eggestad@scali.no>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <Pine.LNX.4.30.0111181602220.1899-100000@elin.scali.no>
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Sender: linux-kernel-owner@vger.kernel.org

All said and done, the file is with correct
permissions (for that matter any binary that I execute
on my filesystem has correct permissions). The only
thing strace tells me is "bad file format". The same
binary works perfectly elsewhere.

I don't think mmap is the problem; you don't need it
in order to run binaries ...

--- Terje Eggestad <terje.eggestad@scali.no> wrote:
> On Sat, 17 Nov 2001, Rock Gordon wrote:
> 
> > Hi,
> >
> > I've written a modest filesystem for fun, it works
> > pretty ok, but when I try to execute binaries from
> it,
> > bash says "cannot execute binary file" ... If I
> copy
> > the same binary elsewhere, it executes perfectly.
> >
> > Does anybody have any clue ?
> 
> Yes
> 
> keep in mind taht the kernel do demand paging of the
> text (code) in our
> executable, meaning that a page of code is not
> loaded into the procs
> memory spce (and thus phys mem) until the proc
> actually tries to exec the
> code page. This is one manifestation of the funny
> term "page fault"!
> 
> I do belive that the current kernel uses mmap to map
> in the exec file text
> segment. (Even if I can hear the ice cracking under
> my feet, never
> actually looked at the code handling execs) but if
> you strace anexec that
> uses shared libs you'll note that the sh.libs are
> mmaped into the process
> space. (also note the MMAP_EXEC flag in the mmap(2)
> man page).
> 
> 
> TJ
> 
> >
> > Regards,
> > Rock
> >
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> -- 
>
_________________________________________________________________________
> 
> Terje Eggestad                 
> terje.eggestad@scali.no
> Scali Scalable Linux Systems    http://www.scali.com
> 
> Olaf Helsets Vei 6              tel:    +47 22 62 89
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