On Mon, Sep 28, 2020 at 02:42:43PM +0200, Arnd Bergmann wrote: > > I need some idea how this numberspace is managed in order to > > understand the code so I can review it, I guess it all makes perfect > > sense but I need some background here. > > I also had never understood this part before, and I'm still not > sure where the 0x900000 actually comes from, though my best > guess is that this was intended as a an OS specific number space, > with '9' being assigned to Linux (similar to the way Itanium and > MIPS do with their respective offsets). By the time EABI got added, > this was apparently no longer considered helpful. It is an OS specific number space, originally designed to allow RISC OS programs to be run under Linux. There was indeed such a project, but that died and the code ripped out. EABI, by using SWI 0 - or more accurately, not reading the SWI opcode, trampled over the ability for RISC OS programs to be run under Linux. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
