it would be nice if there was a separate package containing portable header files for 8051 devices.
It seems not widely known that SDCC provides compiler independent header files.
Yes, the format allows to share the very same header file for SDCC, Keil, Raisonance, IAR, Hi-Tech, Tasking, Crossware, Wickenhaeuser.
The file compiler.h allowing for these portable header files was introduced a few years ago (Mid 2006) by Maarten Brock but up to now adoption both of users and manufacturers has been low.
To encourage usage of this format (avoiding lots of duplicate work, naming inconsistencies and an unnecessary source of errors) SDCC could provide the portable 8051 header files as a separate package.