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Questa intervista e` stata fatta da Davide Barbieri a David Miller, la persona che sta maggiormente lavorando al porting di Linux su Sparc ed e` stata riportata fedelmente in inglese, perche' David usa un linguaggio piuttosto particolare, che anche una ottima traduzione non avrebbe ben reso.

Interview
  1. What is the status of the porting?

    The kernel is extremely stable and works on the following platforms as of this moment:

    1. All sun4c machines
    2. All sun4m machines, even SMP multiprocessor Sparcs. The only nitch is that Cypress MBUS cpus are not supported now, but they will be very soon.

    Userland is very robust, in fact this weekend Red Hat Software has issued a code freeze of the Sparc sources, bug fixes only are allowed, such that they can put together their first official release of Red Hat Linux on the Sparc Platform.

  2. Why use Linux on a Sun?

    Three reasons:

    1. If performance is all you care about, benchmark numbers indicate Linux on the Sparc is faster than Solaris and SunOS on all suported platforms

    2. Stability. Linux on the Sparc can endure endless days without going down when running the operating system robustness tester called 'crashme'. The crashme programs basic strategy is to execute random bytes as if they were program code and see what happens. This tool is very useful for finding operating system bugs and race conditions.

      Some are skeptical as to how indicative crashme is to a real systems actual stability. I usually ask these people what kind of things they think happen on their undergraduate computer science server when the operating systems class has just learned about how to use fork() ;-)

      As it stands I have yet to see SunOS or Solaris, at any patch level, last more than a few minutes at best when crashme is run under them.

    3. The best support money cannot buy. Most people are highly skeptical about using Linux on production machines because of the "support problem" they seem to think exists when one uses free software.

      First point I will make is that none of the people who use Sparc Linux currently have any problems getting their problems fixed/solved. You could ask all of this on the sparclinux mailing lists, and they would tell you. One site which runs Sparc Linux in production 24 hours a day usually gets a bug fixed within 20 minutes when they report them. When I say 20 minutes, I mean within 20 minutes a fixed kernel image is on your machine and you are back up and running without the bug any more. Try to get that from Sun support, good luck and I have a bridge to sell you. ;-)

      Second point I will make, is that even with me telling this to a potential production site that could use and gain from Sparc Linux, they will still not feel comfortable about just "relying" on the Linux community to be this responsive and caring about fixing bugs. To these people my response is that entities like Red Hat Software do exist who can supply (for a fee of course) that person you can get to on the phone providing guarenteed support for your Sparc systems running Linux. Look at Cygnus, their entire buisness is providing support for companies using the GNU C Compiler and other GNU tools for development.


  3. What difficulties are there in a porting like this?

    This may sound strange, but the problems one sees during a port like this are probably similar to the problems a person sees when writing any arbitrary program on a computer. The only difference I can really point out is that the debugging strategies are a bit different for a port of an OS to a new machine.

    To help alleviate this problem early on, I coded in support to use KGDB (Kernel GDB) for the Sparc Linux kernel. This debugging strategy uses a two tiered strategy to debug the entire operating system at the _source_ _code_ level. A small snippet of code runs in the kernel and handles the break points, reading/writing of memory, and communitating to the KGDB server which resides at the other end of one the SparcStations serial lines. The other side runs on any machine running unix, it is just a plain copy of GDB which understands Sparc executables and the like. This GDB invocation gives the small in-kernel debugging code instructions and commands and does so over the serial line.

    Many bugs were found expediantly because of this facility.

  4. Do you have any contact with SUN?

    No, I have no assosciation whatsoever with Sun Microsystems.

    They probably could care less about the port, and in my opinion this is a huge mistake on their part, giving the performance and stability edge Sparc Linux has over thier Proprietary OS's, and the fact that one can get complete source for the Linux Sparc system on top of all that.

  5. How much interest is there on this project?

    The interest is huge. And I expect interest to grow exponentially as the next year progresses, especially with the release of Red Hat Linux on the Sparc.


Later, David S. Miller davem@caip.rutgers.edu

di Davide Barbieri


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