PA-RISC Linux Kernel

Kernel issues

Nothing to brag about, but it’s important, so let’s keep it visible: Kernel Hot Spots and problems Known Issues.

Kernel flavours

The kernel comes in two flavours: 32 bit and 64 bit. The older machines (PA 7xxx processors) only run the 32 bit kernel. Newer machines (PA8xxx processors) may run either 32 or 64 bit kernels. Some machines (depending on the PDC firmware) may only run the 64 bit kernel. The user land is currently only 32 bit ELF, which means that the only interest in running a 64 bit kernel on machines capable of running 32 and 64 bit is accessing more than 4GB of RAM.

Low Level Kernel Code

A collection of notes about various parts of the PA-RISC low level Linux kernel code can be found here:

• Virtual Memory Subsystem

• SMP implementation

• Discontiguous Memory Support

• Device Drivers and interaction with the Device Model

• Interrupts and IO-SAPIC

• EISA, GSC, PCI and IO-MMU implementations

• Futex Implementation

• Locks and Atomic Operations <_atomic_operations>

• Time and high-precision timers.

• Registers and Space Registers

Specific Device Drivers

Here are some drivers that have been written specially for the PA-RISC Linux port, as they concern either PA-RISC-specific devices, or “generic” devices that are only found in PA-RISC systems.

• STI FrameBuffer and STI Console

• AD1889 PCI Soundmax Controller

• Harmony Audio

• SuperIO

• HIL bus and drivers

PA-RISC Hardware/Firmware

Also some bits about PA-RISC specific hardware/firmware and the way it is used by the kernel:

• Processor Dependent Code (PDC)

• Guardian Service Processor (GSP)

• Console Types

Other Gotchas

Bits of information related to the Linux Kernel but not specific to PA-RISC

• Sparse compile-time checks for the Linux kernel

• Kernel Profiling