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Debian GNU/Hurd 2013 Released
jrepin writes "The GNU Hurd is the GNU project's replacement for the Unix kernel. It is a collection of servers that run on the Mach microkernel to implement file systems, network protocols, file access control, and other features that are implemented by the Unix kernel or similar kernels (such as Linux). The Debian GNU/Hurd team announces the release of Debian GNU/Hurd 2013. This is a snapshot of Debian 'sid' at the time of the Debian 'wheezy' release (May 2013), so it is mostly based on the same sources. Debian GNU/Hurd is currently available for the i386 architecture with more than 10,000 software packages available (more than 75% of the Debian archive)."
What are the benefits of using GNU/Hurd 2013?
There aren't any.
Oh come on. April 1st is over. Everyone knows Hurd is a running gag. It's an ancient meme.
Ha, indeed! Someone once tried to convince me that Duke Nukem Forever had been released too. I'm not so stupid that I'd fall for that!
Debian Wheezy - Linux kernel, GNU tools, 100% of software compiled for i386/64.
Debian GNU/Hurd 2013 - Hurd kernel, GNU tools, 75% of software compiled for i386/64 (I'm ready to assume it doesn't have support for other platforms but might be wrong).
Hurd has been conceptual official kernel of GNU project for years (But then Linux came and put Hurd on backburner). Thanks to renewed interest it's development has picked up and therefore we have some actual distribution running with it.
Main problem for Hurd would be support for hardware who needs closed parts (firmware, binary drivers) as Hurd propably is GPL3 which essentially forbids usage of such things without disclosure to user, essentially killing any chances of having binary Nvidia driver supported. Still, most of open source stuff can be ported to be used with it.
user@ubuntubox:~$ stfu This server is going down for shutdown NOW!
If you're interested in understanding microkernel OS architectures, then Hurd might be useful to experiment with. Other than that its pretty close to unusuable as there isn't even basic SATA and USB support (IE you're going to have to install on OLD hardware, or much more likely in a VM where you can supply virtualized IDE).
Honestly, while I certainly don't want to rain on anyone's pet project Hurd has mostly become pointless. Its user space really offers nothing beyond what Linux or other POSIX *nix user spaces offer, and while microkernels are interesting concepts they've never proven to be terribly practical in most applications. Even in terms of microkernel design Hurd is dated. I'd think it would be much more interesting to work on future-looking OSes, say something with a Plan 9-like user space and some more modern experimental kernal with features designed around high core counts and heterogeneous compute resources. Not sure what that is, but I'm sure there are people out there working on stuff like that.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
http://en.wikipedia.org/wiki/GNU_Hurd
Lets start with that. Basically a different kernel (BSD and linux are 'monolitic' kernels, MacOSX is a hybrid).
The idea is everything as much as possible runs in its own process and funnels thru an IPC. The actual kernel does not do much other than scheduling and memory management and IPC.
The idea is you can upgrade your network stack without rebooting the computer. This was very appealing 20 years ago when rebooting to 15+ mins for some bigger hardware. When you can reboot a computer in under 30 seconds it is not as interesting. It is becoming a bit more interesting today with companies wanting '0 downtime' with SLA's. It was also possible that you could run stuff on another machine and it be considered part of the OS. Cool stuff but in practice it ended up being slower than direct calls in many key instances.
Now the downside, they have been working on this since 1987. So work is slow, updates few, resets of the project seem to happen every 3-5 years. At this point you have 4 major OS's to choose from that are all very good (2 of them basically being Unix and one that is a very good clone).
The end user POV of say MacOSX vs Linux vs BSD vs Hurd. Not much. At this point Hurd is basically a research project. Oh I am sure there are a few out there who use it for 'production use'. But not many.
At this stage of Hurd's development, parent is correct. For daily desktop use, Linux is clearly mature enough and Hurd is very probably not.
From the perspective of design, Hurd has some good ideas, as the GNU Web site explains. My favorite is:
So there are design features of the Hurd that make it attractive to developers. I can foresee the Hurd maturing to the point where embedded device makers would seriously consider it, for example.
[Sir Garlon] is the marvellest knight that is now living, for he destroyeth many good knights, for he goeth invisible.
Debian Wheezy - Linux kernel, GNU tools, 100% of software compiled for i386/64.
Wheezy is also available for other CPU architectures, e.g. ARM and MIPS. And, as a preview, you can use it with a FreeBSD kernel on i386 and amd64 instead of the normal Linux kernel.
Debian GNU/Hurd 2013 - Hurd kernel, GNU tools, 75% of software compiled for i386/64 (I'm ready to assume it doesn't have support for other platforms but might be wrong).
You're right, in fact it's only i386, not i386 and amd64.
Microkernel operating systems aren't inherently difficult to construct but there's a very noticeable tradeoff between the performance of a hybrid/monolithic kernel and the security/stability of a microkernel.
The performance hit comes from the hardware isolated process model used by modern microprocessors. Whenever an application needs to do something outside of its own scope, such as request additional memory, access shared resources, or interface with a device driver it makes a system call. In a monolithic system this requires the processor to switch from the running task to the kernel task, perform the requested action, and then switch back to the running task. If the kernel needs to access the tasks memory, it can access it through segmentation or shared memory with ease because the kernel in a monolithic system has no access constraints.
In a microkernel system the processor switches from the running task to an interprocess messaging task (part of the microkernel), which then copies the message to the requested server's buffer, switches to the server task, processes the message, switches back to the messaging task, copies the response back to the original client's buffer, and then switches back to the client task.
Task switches are very expensive in terms of CPU cycles, so minimizing them is key to obtaining performance. Hybrid and Monolithic kernels have a massive performance edge on modern processors because they perform a fraction as many task switches and memory operations whenever a system call is performed.
Wheezy is a GNU/Linux operating system based on the Linux kernel. GNU/Hurd is the GNU operating system based on the Herd kernel. Commonly people simply call GNU/Linux "Linux" but Linux is the kernel which GNU runs atop of.
If you do a bit of research on Hurd the benefits are quite intriguing. One interesting bit is since Hurd is a microkernel, the concept of kernel-space and user-space disappears as everything runs in userspace. The kernel only worries about memory management, process/thread scheduling and message passing. Services are provided by "servers" running in userspace and talk to each other via messages. Users no longer need root access to do simple tasks like installing software, mounting disks, accessing hardware or other tasks which require root access or sudo because they live in kernel space. Instead they talk to the servers directly. The idea is that by moving services to user space, the need to grant users any type of root access (setuid, su or sudo) is removed. There is still a security hierarchy with a "root" user who has full control of the system, but users never need access to that user or group. No need for root access means less chance that the root account can be compromised. Imagine the problem of "privileged ports" disappearing because those services (ftp, http, etc.) no longer need any sort of root access. They are simply allowed to read/write certain files/directories and access the network. If that service is compromised, it can't gain root access.
Some have said microkernels are not necessary or that they impose a larger overhead in the form of message passing. That argument was valid ten plus years ago but today we have quad core 1.5GHz cell phones and PC hardware that is so fast that its stagnated the market. Linus Torvalds famously argued against the microkernel with Andrew Tanenbaum (Minix creator who inspired Torvalds) who is in favor of them. Eric S. Raymond once said about Plan 9 (The planned successor to Unix that failed) "There is a lesson here for ambitious system architects: the most dangerous enemy of a better solution is an existing codebase that is just good enough.". Hurd may never see production use and like Plan 9 be relegated to a research or pet project of a handful of developers interested in operating system design. I hope it succeeds.
Managing the trust graph is why it's hard. Security is always hard. On a monolithic kernel we just say: Uhm, yeah, I trust all these drivers and whatever, even though I probably shouldn't because... well... That's how it works. GNU/HURD/HIRD has a more modular approach that pushes the drivers out of kernel space, but it has some design flaws ( letting a directory node provide its own ".." -- Yikes! ), and the number of developers is next to non-existent.
Furthermore modern processors are designed for monolithic kernels. Just like x86 has a bunch of cruft from when ASM coders wanted more complex instructions (for less / easier coding), Features like Multiple Execution Ring Levels are missing. ARM gives me Two Rings. AMD x86 gives me Two Rings. Intel x86 gives me 4 rings! A ring level essentially is a hardware supported security level. Each ring allows another "mode" of security. So, with only two rings, I can create an OS that has userspace and kernel mode. With 3 rings I can have Kernel, Trusted Driver/Module/Interface, and Userspace. The barriers required to easily create a secure microkernel don't exist. With only 2 rings we have to decide if userspace or kernel mode is where a module belongs -- They don't belong in either! We Need The One Ring to be an intermediary between Ring Zero (which rules them all) and give Ring 2 to the userland, and in the darkness bind them.
Everyone's using monoliths, hardware makers give us 2 rings to make that happen. Hell the hardware even prevents adoption of new (more secure) programming paradigms. Even the virtual memory addressing system in modern chipsets is designed to work best with C. I'm working on a more secure language with separate call and data stacks, and code-pointer overwrite protections for heap data, but the x86 / x64 / ARM platforms I'm working on are built for single stacks, and thus stack smashing or buffer overflow is an inherit design flaw. Segmented memory would be great for securing functions on a per call basis -- Swapping Stacks at will, Super easy Co-Routines... but those bits were sacrificed to the More Memory God, and the registers became a part of the virtual addressing system. On 16 bit code I can do some neat things that I can't do on 32bit mode code without a huge headache, because the hardware doesn't support me doing it.
So, that's why it takes so long. Because we're trying to do stuff in software that the hardware doesn't support. These things are more secure and are great for modularity, but the hardware's designed to do it faster the monolith / C way. Note that to a program it won't matter about whether the filesystem is uber modular, or the device drivers are not in ring 0. Hell, eventually I'll port a C compiler to the multi-stack code.
Note: I don't work on GNU/HURD/HIRD, just develop my own OSs. Yeah, I could work on Linux or other POSIX OSs, but why? That's not going to advance the state of the art in Operating Systems at all. A reliable design is grand for production systems, but to make the leap from the 80's, we're going to need some new hardware to help us out. Got Viruses? Blame the Chip Maker, Language Implementer (not designer), and Operating System. Seriously, they're all doing it WRONG if security is the goal. With a separate call and data stacks on chip, One Ring more, you could actually have the damn security you want.
I'd just like to interject for a moment. What you're referring to as Linux, is in fact, GNU/Linux, or as I've recently taken to calling it, GNU plus Linux.
Sorry, but this war has been fought, and your side lost. I'm not using GNU/Linux/x.org/XFCE anymore than others are using Windows/CrystalReports/Office/PhotoShop.
Listing every single component of the system is stupid. Linux is the kernel, Linux is what gets recognized as the OS. There are a lot of programs that go into making the system usable - each one need not be referenced in the name.
"People who think they know everything are very annoying to those of us who do."-Mark Twain
Stallman has already announced that he is content with Linux as the GNU kernel and that he has lost interest in the Hurd project. Hurd is kept alive now by hobbyists interested in alternative kernel designs, not Free Software demagogues.
If they dumped Hurd now it would be a complete loss of face
Yay it's the daily make shit up about the FSF/RMS thread!
http://blog.reddit.com/2010/07/rms-ama.html
TL;DR
http://lists.gnu.org/archive/html/bug-hurd/2010-08/msg00000.html
Seriously, is it hard to google RMS Hurd before posting crap?
SJW n. One who posts facts.
Naturally I assume you of course call android by the name Linux as well.
Listing every single component of the system is stupid. Linux is the kernel, Linux is what gets recognized as the OS. There are a lot of programs that go into making the system usable - each one need not be referenced in the name.
Mmm, but why do you choose the kernel as the piece so important that you name your whole system after it?
I'm forever seeing posts that say "Windows sucks and Linux rules, because in Linux I can do stuff like {insert neat adhoc bash script}". But you could run that script in a MacOS terminal, with Darwin replacing the Linux kernel. You could run it in Cygwin, with the combination of the Windows Kernel and the Cygwin compatibility libraries replacing the Linux kernel.
Linux is great, but it's a thin layer compared to the collection of GNU (mostly) tools that *actually provide the interface people love*.
The GNU project was a project to develop a free OS and tools.
All works developed for the GNU project were released under the GNU license. Numerous other projects were released under the same license as well.
Linux was a project to develop a free drop-in (and superior) replacement for Minix, and although released under the GNU license, and was distributed with GNU tools, it was never actually part of the GNU project, any more than AIX or HPUX would have become part of the GNU project by replacing their standard tools with GNU equivalents (I personally used an HPUX system at university which had all of the standard tools replaced with GNU ones, but that wouldn't suddenly change the name of that system to GNU/HPUX).
The notion that without the GNU tools, a Linux distribution would not be usable, and therefore the GNU prefix should be applicable to Linux also ought to apply to Minix itself, which like Linux, was never part of the GNU project (and was released under a different license), but was practically unusable out of the box, and most users of it took the source code to the GNU tools, which was freely and readily available, and compiled them to run under Minix to create a usable system. Minux, starting from approximately v 3 onwards, actually started being distributed with the GNU tools to make it more fully functional out of the box, but nobody ever tries to call Minix GNU/Minix.
Linux is Linux. GNU/Linux is just a name that people who were tired of waiting forever for Hurd wanted to call it so they feel like they had some closure.
File under 'M' for 'Manic ranting'
One could argue that the OS is Debian (or Fedora or Ubuntu). All of which use the Linux kernel, and the GNU tools.
Slow down, cowboy! It has been 4 hours since you last posted. You must wait another few hours.
I suppose there's a first time for everything.
This was modded informative because the argument is so old, it's coming back as 'vintage' by hipsters.
Flexible bare-metal recovery for Linux/UNIX
That's entirely pragmatic of you, and that's fine.
But say you wanted to try out an experimental device driver. In Linux it would be a kernel module. If it went wrong, it could potentially cause a kernel panic and halt your entire system. Or, since it has kernel privileges, it could just quietly spy on some element of your system and phone home with your confidential data without you knowing.
On a microkernel, your experimental device driver would run in separate memory space to other components. If the experimental driver crashes out, the rest of the system keeps going. It can't spy on your other components, because its access is restricted.
It may not address a need *you* have, but it may well be useful to others.
Excellent point! I'll remember that one. I just cut to the chase and call all my systems debian.
Because people like an easy, pronounceable, memorable label for things.
It usually goes like:
GNU: Do you spell it out, "gee en you"? Or is it "new" like the wildebeest? And what's with the recursive acronym (GNU's Not Unix)? Why do you geeks pick such awkward names?
Linux: Only two possible pronunciations, both easy.
Given a choice between technically correct and easy, most people will pick easy.
To pretend you are still a hippy in the 70's?
They aren't. There are many microkernel OSes out there that are successful, like QNX (which has made plenty of noise about how it runs nuclear reactors and such). Hell, even Windows was completely microkernel at one point.
The main problem is performance. This comes from two problems - repeated kernel requests, and IPC.
Kernel requests happen because device drivers are run at application level (which provides great isolation). However, device drivers tend to require a lot of stuff at the kernel level (which is why they're typically in the kernel...) - things like interrupts, physical memory access, DMA, memory allocations (both physical and virtual), and such. Each one of those things it can't do alone (because well, it's an application - if applications can do those things, your microkernel is no better than DOS - the goal is to isolate things from each other). So it becomes an kernel API call to request an interrupt, to register an event object (the interrupt handler runs in the driver server as an interrupt thread), to get memory mappings installed, etc. Each API call is a system call in the end, which are generally expensive things because they require context saving and switching (some microkernel OSes use "thread migration" to mitigate this) and so forth.
The second problem is IPC. All the servers are isolated from each other and can only communicate through IPC mechanisms. So a microkernel has to end up being a message routing and forwarding service as well. Let's say an application wants to read a file it has open. It calls read(), which traps into the kernel (system call, after all), which the kernel then sends a message to the server which can handle the call (filesystem), so it passes the message to the filesystem server and then switches back to user mode so the filesystem server can handle it. The filesystem server then translates it to a block and issues a read to the partition driver (which if it's a separate server is yet another user-kernel-user transition), which then goes to the disk driver (u-k-u). From here, it goes to the bus handler (because said disk can be on SATA, IDE, USB, Firewire) where the transfer actually happens, and then the message winds it way back to the disk driver, the partition driver, the filesystem driver, then the application.
Switching from user to kernel is expensive - generally requires generating a software interrupt (system call) which triggers into the kernel's exception handler which then has to decode the request. Switching back is generally cheaper (usually just a return instruction which sets the proper mode bits), but you're still taking several mode switches per API call.
No big surprise, these things add up into a ton of cycles.
Microkernel OSes have developed means to alleviate the issue - thread migration being a big one (typically a server is implemented as a thread waiting on a mailbox, it gets the message then handles it). Thread migration means the application's thread context isn't saved, but migrated to the kernel, then passed onto the servers as necessary so instead of having to wake up threads and run the server loop, it becomes more expensive function calls, almost like RPC except the thread that called it is where it's executing on.
In a monolithic OS like Linux, all those messages and IPC are reduced down to function calls (usually through function pointers) - so the application making the system call becomes the only transition - the virtual filesystem handles the call, calls the filesystem driver, which calls the partition driver, which calls the disk driver, which calls the bus driver, ... and then they return up the stack like a typical subroutine call.
Oh, and Windows NT 3.51 did this as well. Guess what? Graphics performance sucked, which is why in NT 4, Microsoft moved the graphics driver into ring0 (kernel mode), thus creating the ability for poorly written graphics drivers to crash the entire OS. But, graphics are faster because you're not shuffling so much messages around. I think Windows has steadily put more and more of the graphics stack in the kernel since then, as well.
The Mayans were pointing to the dawn of a new era, the age of Linux on the desktop, which supposedly will last for the next B'ak'tun until Hurd is up and running on the L4 microkernel.
Main problem for Hurd would be support for hardware who needs closed parts (firmware, binary drivers) as Hurd propably is GPL3 which essentially forbids usage of such things without disclosure to user, essentially killing any chances of having binary Nvidia driver supported. Still, most of open source stuff can be ported to be used with it.
Yeah, that is what would make it pretty much a non starter on the desktop, since it's probably GPL3 - or else, its rationale for existence separate from Linux is as strong as the rationale for East Germany or North Korea existing. Since binary blobs would be banned here, they'd be limited to Intel & AMD GPUs, however bad, and then, on top of that, run X, and GNOME 3.whatever in fallback mode, or in real mode if the drivers are liberated. In short, the best use of HURD, where it would be almost guaranteed to work right, is in CLI mode, if one is like RMS and lives in an emacs world. In which case, the login script could just as well include that, one goes into emacs, and then is off doing everything that one does there.
Just wondering if the "Libre-" Linux crowd will celebrate this, or release a list of 50 reasons why Debian doesn't pass the purity test and therefore, Debian Hurd can't be endorsed? I sure wish gNewSense comes up w/ a HURD distro based on this one.