(REG)The short answer is why should we? The longer answer is that experience has shown that microkernels have poor performance compared to monolithic kernels. Microkernels have a fundamental design problem, where different components of the kernel cannot interact without passing a privilege barrier (which is expensive). Microkernel advocates claim this is a feature, as it increases modularity and protects one part of the kernel from another. Whether this is a feature or a mis-feature is in the eye of the beholder, but it is clear that there is a performance cost inherent in the microkernel design. This is a cost the Linux kernel developers (and apparently, the users) are unwilling to bear. There are projects which have ported the Linux kernel to generic microkernels (such as), usually making Linux a "personality". There are also other projects to create microkernel-based Unix-like implementations. Here is a short list:
MkLinux was funded by Apple, and runs Linux on PowerPC Macs. It is available at:. An x86 version is also available. Note that there is now a native Linux kernel for the PowerPC which is much faster, and is actively maintained. MkLinux has become a historical footnote.
The Hurd is a microkernel-based Unix, and is supposed to be the promisedkernel. It sits on top of Mach3. Theprovides a fullfor the Hurd.
FIASCO is another project for creating MicroKernel LINUX. Seefor details.
There is arelated to this subject, dating back from 1992, with posts from Linus,,,,and others. Nice reading on a rainy afternoon. It's fascinating to see how some predictions (which seemed rather reasonable at the time) have proved wrong over the years (for example, that we would all be using RISC chips by 1998).
