One of the CPU architectures continuing to be supported by the mainline Linux kernel but rarely ever seeing any code activity is the SPARC64 architecture port for the once-interesting processors from Sun Microsystems.
Sent out today was the first SPARC64 Linux patch series in a long, long time catching my eye. Linutronix developer Thomas Weißschuh is working on converting SPARC64 over to using the generic vDSO library within the Linux kernel. SPARC64 is the last architecture supported by the mainline kernel not using this generic vDSO code that allows for a lot of code sharing cross-architecture. Linux’s Virtual Dynamic Shared Object (vDSO) allows exposing select system calls directly to user-space for avoiding the overhead of the standard system call mechanism.
SPARC64 was the last architecture not using the generic vDSO library code that in turn prevented some necessary code clean-ups. With this patch series transitioning the SPARC code to the generic vDSO infrastructure saves several hundred lines of code and slightly reducing the SPARC maintenance burden.
With Oracle having ceased SPARC CPU development eight years ago and SPARC platforms before that already being rare — and those big SPARC customers having tended to deploy with Solaris — we’ll see how much longer the SPARC support continues lasting within the mainline Linux kernel.
