what is the relationship between sbus and jbus(jbi)?
Hi all!
In linux ,there is a dir named "\drivers\sbus".In "Fast Ethernet, Parallel Port, SCSI" document, signales of FEPS are named "SBus Interface Signals" .First I took sbus as J-Bus.But after comparing the "SBus Interface Signals" of FEPS with J-Bus,I found they are total different.
I am puzzled with it. And I found it was difficult to find any documents or specfications .Will you give me a hand ?Thanks!
[429 byte] By [
openidea] at [2007-11-26 10:11:47]
# 1
> In linux ,there is a dir named "\drivers\sbus". In "Fast Ethernet, Parallel Port, SCSI" document,
> signales of FEPS are named "SBus Interface Signals". First I took sbus as J-Bus.But after comparing
> the "SBus Interface Signals" of FEPS with J-Bus, I found they are total different. Am puzzled with it.
The short answer to "what is the relationship between Sbus and Jbus?" is "practically none".They're two bus technologies, separated by about a decade in time. The main thing they have in common is that they were both used by Sun.
Sbus is an old bus that was used in early/mid-1990's Sun systems.I believe it was first used on the SPARCstation-1 (the first "pizza box") workstation product. It ran at something like a 25-50MHz bus frequency (fine then, but slow by today's standards).Sbus hasn't been used in production systems for many years now.
Jbus is an entirely different, faster, higher-performance bus, that is in current use.Notably, it's used in the UltraSPARC T1-based T1000 and T2000 systems from Sun.
Since OpenSPARC T1 is the UltraSPARC T1 design, that's the bus you'll see in OpenSPARC T1.Jbus is supported by Solaris 10, Ubuntu Linux, and another Linux distro that was just announced (don't recall the name). Since it's in multiple Linuxes, I'm sure that Jbus support is included in the code that David Miller deposited at kernel.org. I believe support for Jbus is also being included in *BSD.
