Re: GSoC 2020 - The NetBSD Foundation - Emulating linux timer.. syscalls

2020-03-31 Thread Stephen Borrill
On 22/03/2020 21:34, Humayun Mulla wrote:
> Hi,
> 
> My name is Humayun Mulla, I am a graduate student pursuing MS in
> Computer Science from State University of New York, Binghamton. I have a
> total work experience of 6 years of which 1 year as an Assistant
> Professor and 5 years in the software industry.  
> My Github link - https://github.com/HumayunMulla & LinkedIn profile -
> https://www.linkedin.com/in/humayun-mulla-02719727/.
> 
> I have taken an Operating System course in the previous semester and I
> have developed an interest in understanding how things work at such root
> level in the computer system. As a part of the course I have done
> different projects which vary from developing a shell that can execute
> all the commands given to it. In addition to that added some features to
> the program so that it can do I/O redirection and implemented
> inter-process communication. Also another assignment involved developing
> a kernel module that does 5-level page walk and printing the physical
> address of any given process ID. The last project that I did was to
> solve producer-consumer problem using a named pipe, i.e. by developing
> character device driver that can act as an interface between multiple
> producers & consumers.
> 
> I know I am late to approach you but I taught of better to learn to walk
> first and then run. Therefore I spent the last couple of weeks in
> understanding and implementing Live VM Migration. And also understanding
> about how timer system calls work in Linux environment.
> 
> I wanted to know if there are any pre-requisite tasks that I need to
> complete before submission of my application. I am looking forward to
> work under your mentor-ship on emulating linux timer.. syscalls using my
> knowledge and your guidance. Hoping to hear from you soon. Thank you for
> your time and consideration.

As Christos said, you should ensure you can actually get NetBSD running
on your chosen device or emulator. Better still, ensure you can build a
kernel and boot from your built kernel. I suggest you start with amd64,
but the finished code will need to work on i386 too.

As you suggest, you should also try to understand how the timer system
calls work on Linux and think about how you could test the operation.

-- 
Stephen


Re: All (?) network tests failing

2020-03-31 Thread Robert Elz
Date:Mon, 30 Mar 2020 14:25:01 -0400
From:Christos Zoulas 
Message-ID:  <3d3ac2b9-5e6e-400c-9a4b-10742c90c...@zoulas.com>

  | All the tests are failing for you the same way:
  | rump.route: SO_RERROR: Socket operation on non-socket
  |  <>I doubt that my gif change affected that. This smells to me like the =
  | rump fd hijack is not
  | working either because we have some new system call involved or =
  | something is messing
  | up the file descriptors.

If something has decided to move an fd out of the low number space
(not all that high necessarily) then rumphijack will confuse the fd
from user space with one of its own (it isn't very smart about that,
and bases the decision entirely upon the value of the fd it sees).

I wonder if something changte to try and be "nice" to other programs
by moving a "background" fd out of the 0..50 type space usually used by
user fd's and somewhere up > 100 ? (the fd space really runs up to the
thousands, but nothing we run ATF/Rump tests against ever needs more than
a small number of fd's, so they never naturally get out of the low number
area).

kre



Re: All (?) network tests failing

2020-03-31 Thread Robert Elz
Date:Mon, 30 Mar 2020 20:47:12 -0400
From:Christos Zoulas 
Message-ID:  

  | Unfortunately they still work for me after a clean build. I am going to =
  | try to download a standard build...

Does your tree have any uncommitted changes?

(I see the same 200+ tests failing as everyone else seems to see, on
amd64 (I do my tests in a XEN DomU), but I note b5 is seeing the same
on i386 (at least) as well).

kre