Re: Virtual Address Space

2016-10-02 Thread Madhu K 
Hi All,

Thank you so much for all your answers.

Regards,
Madhu

On Sun, Oct 2, 2016 at 8:22 AM, Arshad Hussain 
wrote:

>
> On 30-Sep-2016, at 10:10 pm, Román Martínez  wrote:
>
> > Hi,
> >
> > I compile main.s and it generates main.o. With objdump I can see:
> >
> >  <_start>:
> >0: b8 01 00 00 00  mov$0x1,%eax
> >5: bb 00 00 00 00  mov$0x0,%ebx
> >a: cd 80   int$0x80
> >
> > After link main.o it generates main. With objdump I now can see:
> >
> > 00400078 <_start>:
> >   400078: b8 01 00 00 00  mov$0x1,%eax
> >   40007d: bb 00 00 00 00  mov$0x0,%ebx
> >   400082: cd 80   int$0x80
> >
> > So, linker generates virtual address, doesn't it? But why it starts at
> 400078 and not in other any location? Is there any logic here? A virtual
> address can start at 0?
> >
> The linker script would normally leave out some area and _not_ start from
> 0. (although this is not
> an absolute necessity ). It will pick up and valid virtual address and
> assign start of .text,.bss and
> .stack. This is possible because we now have virtual memory. And every
> program thinks that it
> has _all_ the memory for itself.  So, 400078 is perfectly valid virtual
> address space and linker
> has chosen this for this executable.
>
> Also note that if the address space is getting shifted by little , this is
> because of the KASLR
> (layout randomisation) - If this is disabled then the linker would
> generate the same virtual
> address for all the executable every time.
>
>
>
> 
>
>
>
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Re: Linux Kernel Based Research Projects

2016-10-02 Thread Daniel Baluta 
On Sun, Oct 2, 2016 at 2:54 PM, Shyam Saini  wrote:
> Hi everyone,
>
> I'm final year computer science undergraduate student. I want to do my
> major project based on linux kernel.
>
> Would you please suggest me some areas in the kernel which have some
> projects. To be more specific, I want know on going research areas in
> kernel. Or some ideas which are not yet implemented.

Would you be interested in taking a look at lguest? [1]

I will be having a presentation about lguest and how one learn
linux kernel internals by studying lguest code
this week at LinuxCon Europe [2]

Porting it on x86_64 or any other architecture will be a very cool project
but I warn you it won't be trivial :).

thanks,
Daniel.

[1] http://lguest.ozlabs.org/
[2] http://sched.co/7o92

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Re: Linux Kernel Based Research Projects

2016-10-02 Thread Robert P. J. Day 
On Sun, 2 Oct 2016, Shyam Saini wrote:

> Hi everyone,
>
> I'm final year computer science undergraduate student. I want to do
> my major project based on linux kernel.
>
> Would you please suggest me some areas in the kernel which have some
> projects. To be more specific, I want know on going research areas
> in kernel. Or some ideas which are not yet implemented.

  as someone on this list once suggested, saying you want to work on
the linux kernel and want someone to suggest a subsystem is like
saying you want to write a book and could someone suggest a topic for
you to write about.

  if you haven't even progressed to the point where you know what part
of the kernel interests you, you shouldn't be asking for projects.
it's not everyone else's responsibility to do your research for you.

rday

-- 


Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca

Twitter:   http://twitter.com/rpjday
LinkedIn:   http://ca.linkedin.com/in/rpjday



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Re: Booting of Linux kernel

2016-10-02 Thread Miles Fidelman 
On Tue, Sep 6, 2016, 8:10 PM Er Krishna > wrote:



Hi all

I have a basic question for understanding :

If we want to boot the Linux kernel without bootloader what needs
to be done?

In other words what all the core subsystem like memory and all
needs initialisation by bootloader and if bootloader is not there
then how to do it ?




The role of a bootloader is to load and initialize an operating system - 
so, in essence, you're asking "what does a bootloader do?" and "how do I 
write a bootloader?"


Perhaps the easiest way to answer your question is to suggest that you 
study the Linux boot process - and how it proceeds from power up, to 
BIOS, to LILO or Grub.  Your answer is in the details.


Miles Fidelman



--
In theory, there is no difference between theory and practice.
In practice, there is.   Yogi Berra

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Linux Kernel Based Research Projects

2016-10-02 Thread Shyam Saini 
Hi everyone,

I'm final year computer science undergraduate student. I want to do my
major project based on linux kernel.

Would you please suggest me some areas in the kernel which have some
projects. To be more specific, I want know on going research areas in
kernel. Or some ideas which are not yet implemented.

Thanks,
Shyam

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