Walleij: Setting up the Arm32 architecture
Walleij: Setting up the Arm32 architecture
Posted Nov 4, 2020 9:26 UTC (Wed) by farnz (subscriber, #17727)Parent article: Walleij: Setting up the Arm32 architecture
For those people wondering (as I did) what the "address exception" vector that Linus refers to is, and why it's no longer in use; it's the vector ARM26 systems (ARMv1/ARMv2 architecture, ARM1/2/3 chips) used when a virtual address outside the 26 bit bus range was accessed. Because ARM32 systems have a 32 bit address bus and 32 bit address calculations (compared to ARM26 with 26 bit address bus and 32 bit address calculations), this vector is no longer needed.
Posted Nov 4, 2020 22:18 UTC (Wed)
by linusw (subscriber, #40300)
[Link] (1 responses)
Posted Nov 5, 2020 9:46 UTC (Thu)
by farnz (subscriber, #17727)
[Link]
No, thank you for a great set of articles!
I just happened to know where to look for details of that vector, as I have vague memories of it from the Acorn Archimedes days. IIRC, ARMv4 can optionally run in ARM26 mode (at the discretion of the silicon designer), and ARMv5 onwards is ARM32 only. It's only ARMv1/ARMv2 that must run in ARM26 mode, and the last ARMv2 series chip was the ARM3.
ARM naming up until Cortex was confusing as all get-out, since the ARM610 is an ARMv3 chip, and the first ARMv5 chip is the ARM9 series, while ARM7, ARM8 and ARM9 chips are all ARMv4.
Walleij: Setting up the Arm32 architecture
Walleij: Setting up the Arm32 architecture