Porting Linux to the DEC Alpha: The Kernel and Shell

As mentioned above, we need to deploy some sort of BIOS-emulation facility so that we can execute the proprietary initialization code on some expansion cards. While initial code exists and works, it does not support the real-mode 32-bit instructions that are used in the BIOSes of some cards.

We need to tackle the great unsolved problem of floating-point exception handling. Programs that are floating-point intensive are not likely to work until this is done.

We need to write a character-cell driver and an X server for the TGA graphics adapter that is provided with Multia and several other Digital Alpha systems.

We desperately need shared libraries! As of this writing, the statically-linked executables in Linux/Alpha are rather large (around 200Kb for a typical utility, several megabytes for the X server). Shared libraries will decrease both disk space requirements and virtual-memory usage.

We need to work on compiler optimizations. The Alpha support in gcc does very good optimizations in some places, not so good in others. In addition, the compiler does not yet take advantage of Alpha's multiple-instruction issue feature. This feature allows more than one instruction to be issued per clock cycle, but only certain combinations are allowed. By carefully rearranging the instructions in the executable, one can take advantage of this feature and achieve significant performance improvements.