From the begining of the project (1998, December) until today, the porting process crossed three differents phases in the developpment. Each of these phases marked an important step in the PA/Linux evolution.
During the first phase of the project, the main goal was to make linux booting (only booting, not running) a linux kernel on a PA-RISC box. This required a compiler, a loader and a builded kernel. As mentionned before, GNU cc compilers were available for PA-RISC. But, only the 64 bits compiler produced ELF binary coded. Since developpers wished to only concentrate their effort on 32 bits binary file, they hacked this last compiler to produce code using 32 bits instructions set only. CLose after, a PA/Linux kernel were build, and booted by the current HP-UX loader, HILO.
This first boot, realised by Helge Deller, was celebrated accross the world by all the project members in July 1999, even though this kernel died few seconds after the boot. The only features managed by this kernel was basics I/O with PDC and the virtual memory manager. About the virtual memory, some PA-RISC processors were able to manage a part of the TLB inside themself. Since this particularity was not generalized on the whole processors set, it hasn't been exploited to keep the same VMM on each PA-RISC box.
This first phase was very important since at this moment, while some developpers continued to improve the compiler and the loader, others could began to develop kernel functionalities inside the kernel and adding usefull drivers. Indeed, the kernel hardly used only PDC calls to get output on the serial port, and it wasn't able to use itself neither ethernet card nor SCSI controller.