My understanding is that Docker on Windows currently uses a "regular VM" under the hood. WSL2 (and Docker) will switch to using a lightweight VM. But what does this actually mean; is it just using a smaller initial memory foot print with some memory passthrough technnique, or is there more to it?
TL;DR
The big change is in the move from a virtualized Linux system call interpreter for the Windows kernel in WSL to a full-on Linux kernel provided in WSL2. This move dramatically cuts down on virtualization overhead.
Juicy Details
Directly from the DevBlogs Post on the announcement of WSL2:
Microsoft will be shipping a Linux kernel with Windows ... This kernel has been specially tuned for WSL 2. It has been optimized for size and performance to give an amazing Linux experience on Windows.
This is a departure from the ways of the current (as of writing) WSL which doesn't make use of a proper Linux kernel, demonstrated in the original WSL overview from 2016.
WSL executes unmodified Linux ELF64 binaries by virtualizing a Linux kernel interface on top of the Windows NT kernel.
The WSL LXCore service runs an interpreter of sorts for native Linux system calls as well as running its own VolFs and DriveFs operations to provide file access between WSL and Windows 10, which essentially performs the role of a traditional VM's translation layer the likes of VirtualBox.
Citation: MSDN Blog
Little is known as of yet about the exact system employed for WSL2, what we do know is from the Build2019 WSL2 talk. To help answer the question regarding file system changes and the light VM:
Here, we see that the Linux kernel runs alongside the NT Kernel instead of as a virtualized environment on top of it. (as a Windows service). The lightweight VM likely comes into play for facilitating the necessary interactions between the two kernels.
This gives a peek into the inner workings of that interoperability layer. Discussed verbally in the Build2019 talk, the two kernels serve each other files via natively hosted file servers (inaccessible to the Windows userspace via means other than WSL2).
Again, much is still up in the air from our perspective as users due to the limited details currently available to us at the time of writing.
I need to test my C code for 32- and 64-bit versions of Windows (XP and 7) and Linux. But I have got access only to their 64-bit installations.
Question: Is it possible to use some boot-time settings or other hacks to run/emulate these OSes in 32-bit mode? If not, is there any other way to test the portability of my C code?
Note: The C code in question is not a full-fledged application but rather a .dll/.so file.
Neither Linux nor Windows 64Bit can run as 32Bit OS. Also, while you can run 32Bit executables on the 64Bit OS, it is not quite the same as running the same under a 32Bit OS. But it might work as a quick screening test. Besides, you certainly want that to work as well, right?
Your choices are full multi-boot setup, using VMs (might hide/expose bugs), being content with the emulation layer or running the other OS's on different hardware.
BTW: If you have Windows 64Bit, the license allows you to run 32Bit instead and vice versa. Anyway, you might want to check different language versions as well...
I just want know why some games are only Windows-based and won't run on other OSs like Mac OS X and Linux. What makes them different, and how does the program know that the OS is Windows, Linux, or Mac?
Also, similarly, why won't a Windows 7 32-bit driver work on 64-bit and vice versa?
Besides how Mac and Linux use a different executable type (they use Mach-O and ELF, as far as I've seen) than Windows (PE), if the executable loader was able to parse everything and load it into memory, many things can go wrong. Library calls, such as printf(3) rely on underlying system calls, which calls the kernel of the OS. In the case of printf(3), it calls fstat(2), sbrk(2) and write(2). (Note that this is the case under the newlib library; I am unsure about the other standard C libraries.) As far as you know, the system call interface for Windows can be very different from the one Linux uses, and Windows may even be missing a few system calls that Linux has (like fork(2))
is there any gui tools like gnome system monitor in solaris for monitoring processes? or is it possible to get the gnome system monitor binary pkg for solaris os ?
You don't specify which version of Solaris - recent ones include gnome-system-monitor already.
Additional gnome software for older Solaris versions may be available from various projects that make open source software packages available for Solaris, such as SunFreeware, Blastwave, and OpenCSW
The CDE desktop included in Solaris 2.6 through Solaris 10 also includes a couple of simpler process monitoring tools - sdtprocess and sdtperfmeter.
If you dont mind me asking what is the need for a gui?
the command top will give you everything you need but in a terminal?!?
anyway /usr/dt/bin/sdtperfmeter is on older releases but this WONT give you processes
gnome-system-monitor should be installed on newer releases, and this WILL give you processes.
If the gnome-system-monitor command doesn't work top will.
How about GKrellm? That is popular under the Gnome suite running on Linux.
Does anyone know of a good software development framework or similar that has the following properties?
Cross platform: it should be runnable on XP, Vista, OSX and common versions of Linux (such as Ubuntu and Kubuntu).
No installation: Be able to run the software from a USB stick without having to copy anything to the host machine.
Have good GUI support (this is why this question doesn't give a suitable answer, as far as I can tell).
Permissive licensing such as LGPL or BSD or such.
Among the softer requirements are having a set of abstractions for the most common backend functionality, such as sockets, file IO, and so on (There is usually some platform specific adaptations necessary), and supporting a good language such as Python or C++, though it is usually fun to learn a new one (i.e. not perl).
I think possible candidates are Qt 4.5 or above (but IFAIK Qt software will not run on Vista without any installation(?)), some wxWidgets or maybe wxPython solution, perhaps gtkmm. The examples I have found have failed on one or another of the requirements. This does not mean that no such examples exist, it just means that I have not found any. So I was wondering if anyone out there know of any existing solutions to this?
Some clarifications;
By "framework" I mean something like Qt or gtkmm or python with a widget package.
This is about being able to run the finished product on multiple platforms, from a stick, without installation, it is not about having a portable development environment.
It is not a boot stick.
It is ok to have to build the software specifically for the different targets, if necessary.
The use case I am seeing is that you have some software that you rely on (such as project planning, administration of information, analysis tools or similar) that:
does not rely on having an internet connection being available.
is run on different host machines where it is not really ok to install anything.
is moved by a user via a physical medium (such as a USB stick).
is run on different operating systems, such as Windows, Vista, Ubuntu, OSX.
works on the same data on these different hosts (the data can be stored on the host or on the stick).
is not really restricted in how big the bundled framework is (unless it is several gigabytes, which is not really realistic).
It is also ok to have parallel installations on the stick as long as the software behaves the same and can work on the same data when run on the different targets.
A different view on the use case would be that I have five newly installed machines with Vista, XP, OSX, Ubuntu and Kubuntu respectively in front of me. I would like to, without having to install anything new on the machines, be able to run the same software from a single USB stick (meeting the above GUI requirements and so on) on each of these five machines (though, if necessary from different bundles on the stick).
Is this possible?
Edit:
I have experimented a little with a Qt app that uses some widgets and a sqlite database. It was easy to get it to work on an ubuntu dist and on osx. For windows xp and vista I had to copy QtCored4.dll, QtGuid4.dll, QtSqld4.dll and mingwm10.dll to distribution directory (this was debug code) and I copied the qsqlited4.dll to a folder named "sqldrivers" in the distribution directory.
You mention wxWidgets but dismiss it as failing at least one of the requirements.
I don't know what your requirements are and in what way wxWidgets wouldn't work for you, but IMO it does fulfill them:
Cross platform: it should be runnable on XP, Vista, OSX and common versions of Linux.
It does run on those platforms, but "common versions of Linux" isn't good enough, as you can never be sure that the necessary GUI libraries for wxGTK (which should not be linked to statically) will be installed. This is however a problem for other solutions as well, unless you plan to put everything onto the stick.
No installation: Be able to run the software from a USB stick without having to copy anything to the host machine.
See the previous point, you would need to specify which libraries are needed on Linux. Also you could specify at build time not to use some of the system-provided libraries (for example for graphics, compression, regexes) but to use the wxWidgets-internal libraries instead.
Have good GUI support
Check.
Permissive licensing such as LGPL or BSD or such.
Check. You can statically link wxWidgets into your application too.
supporting a good language such as Python or C++
Supports both, and there are bindings to other languages as well.
having a set of abstractions for the most common backend functionality, such as sockets, file IO, and so on
It does have some abstractions like that, but you can link to other cross-platform libraries as well.
We use wxWidgets for FlameRobin, a graphical administration program for the Firebird SQL server. It has active ports to Windows, Linux and Mac OS X, and has been compiled for at least some BSD variant and Solaris as well. It definitely runs from a stick on Windows, I haven't tried with Linux or Mac OS X, but I don't see why it shouldn't there too.
Java.
It has GUI support.
It provides your network/file/etc. abstractions.
It is cross-platform. Most platforms you can think of have a JRE available.
No need to install a JRE. Most users probably already have one, and if not, you can run the appropriate JRE right off the stick.
You can provide several startup scripts for various platforms to run the app under the appropriate JRE.
Something else to consider is HTML+Javascript. :D
You can look at Mono it cross platform, has GUI (GTK+, or Winforms 2.0) and I can execute code without installing.
This might not be crossplatform, but is maybe even better, it dont even use the platform : linux on a stick :-)
The subtitle is
Take your Java workspaces wherever you go on a USB key
Here with java and eclipse, but nothing stops you there of course.
http://knol.google.com/k/inderjeet-singh/installing-a-ubuntu-hardy-heron-java/1j9pj7d01g86i/2#
Well, it depends on what you mean by 'package'. Kylix came close to being such a thing. It was QT based, and it allowed you to write once and compile for Windows + Linux. However, it was not an open source solution.
I asked a similar question in this link
http://www.24hsoftware.com/DevelopersForum/CrossPlatform-C-Library.html
and the best asnswer seems to be QT.
I have started using QT, but it is not as easy as I expected mainly due to deployment problems due to the DLL hell, Winsxs hell and manifest hell.
Tclkit is a single-file, self-contained Tcl/Tk system. The mac version I have is about 3.8 megs. You can get a version for just about any modern OS. I carry around a thumb drive that has mac, windows and linux binaries so I can run my scripts on any platform. No install is required, just copy one file wherever you want.
The most recent versions of tcklit use native, themed widgets (though, on *nix there really isn't a single "native" set of widgets...)