/proc/sys/vm/mmap_min_addr missing

[Valery Reznic]

----- Original Message -----
> From: Baruch Siach <baruch at tkos.co.il>
> To: Valery Reznic <valery_reznic at yahoo.com>
> Cc: linux-il <linux-il at cs.huji.ac.il>
> Sent: Tuesday, January 15, 2013 9:07 AM
> Subject: Re: /proc/sys/vm/mmap_min_addr missing
> 
> Hi Valery,
> 
> On Mon, Jan 14, 2013 at 01:40:14PM -0800, Valery Reznic wrote:
>>  Recently I stumbled upon some mystery that I can't understand.
>>  My Google search bring no results.
>> 
>>  I have 3 VM with different Linuxes that run under QEMU and now I noticed 
> that
>>  all of them don't have /proc/sys/vm/mmap_min_addr files (/proc is 
> mounted)
>> 
>>  I am sure that this file was here some time ago.
>>  I didn't recompile kernel in any of those VMs, don't upgrade QEMU - 
> nothing of the sort.
>> 
>>  But those VMs where started and stopped multiple times.
>> 
>>  So my questions:
>>  1. What happened, where this file gone?
>>  2. How can I get it back?
> 
> The existence of mmap_min_addr depends on the CONFIG_MMU kernel config symbol 
No. It's x86-64 and ARM. And I remember seeing this file before.

But config is a good idea, thanks I'll check it.

Valery

> (see kernel/sysctl.c).  Are you by any chance running MMU-less architectures 
> under QEMU? If so, there is nothing you can do to get mmap_min_addr back, as 
> this is an inherent limitation of MMU-less architectures.
> 
>>  My host system (Fedora 12, x86-64) has this file.
> 
> baruch
> 
> -- 
>      http://baruch.siach.name/blog/                  ~. .~   Tk Open Systems
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>