The current release of Fiasco is
1.2, released 26 Sep 2005.
It includes Fiasco-UX as a sub-architecture.
The newest version is available from
The following list summarizes what's missing in Fiasco-UX compared to
the native Fiasco kernel.
|Supported Linux Kernels
||2.2.x up to 2.6.x (earlier kernels untested)
|Supported Processor Architectures
||x86 only (Intel, AMD, other x86 compatibles)
|Supported L4 ABIs
||V.2 and X.0
- Port I/O and I/O flexpages (not planned)
- Small address spaces (not planned)
- Support for fast ring transitions using sysenter/sysexit
Because Fiasco-UX emulates a µ-kernel in user-mode, there is a
performance penalty of a factor of about 50 to 100 for context switches compared
to the native Fiasco kernel. This is comparable to the performance loss
of User-Mode-Linux compared to native Linux.
Fiasco-UX doesn't have the real-time properties of the native Fiasco kernel.
What's up next:
- Virtual devices and adapter spaces