linux-kernel - Re: UML fails to locate address space

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Message-ID: <20080520135238.GB6990@c2.user-mode-linux.org>
Date:	Tue, 20 May 2008 09:52:38 -0400
From:	Jeff Dike <jdike@...toit.com>
To:	Tom Spink <tspink@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: UML fails to locate address space

On Tue, May 20, 2008 at 12:08:24PM +0100, Tom Spink wrote:
> I've just recently pulled the latest GIT and compiled UML, however,
> when I run it a message appears saying "Locating the top of the
> address space... Address 0x0 no good?" and the program exits.

Can you strace it and send me the output?

> After some digging, it appears that page_ok is returning false when
> checking 'bottom', in os_get_task_size
> (arch/um/os-Linux/sys-i386/task_size.c:96).  After running through
> GDB, it seems that in line 31 of that file is where the segfault
> occurs:
> 
> n = *address;
> 
> i.e. when trying to read from the address space (at address zero).

The segfaults are on purpose - it will trap SIGSEGV and longjmp out of
the handler and mark the affected address as not-usable.

    	       	  Jeff

-- 
Work email - jdike at linux dot intel dot com
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