Describes what to expect from the run-time environment when
starting eCos configured for RAM startup.
The option name may be a bit of a
misnomer. Think of it as "there's a ROM monitor X on the
board... work with it." Which might only mean "so the serial is
already initialized; don't bother to do it a 2nd time" whilst
still taking over the world (ie. not working with it, just not
overwriting its prior good works).
CYGSEM_HAL_USE_ROM_MONITOR_GDB_stubs and
CYGSEM_HAL_USE_ROM_MONITOR_CygMon are most
common. Depending on other options, these may allow eCos to use
services provided by the ROM monitor (see eCos/ROM Monitor Calling
Interface). Running under these environments also usually
imply full debugging features with GDB.
When working with older ROM monitors (which do
not support the calling interface), the options are used to infer
that we are likely to be connected to a GDB - and therefore $O
packets should be used by hal_diag rather than plain text by
default. Which is more working with a likely other end of the
serial line than working with the ROM itself.
Other variants exist, such as CYGSEM_HAL_USE_ROM_MONITOR_PMON
(used by the VRC4374 HAL). These may or may not provide all of the
features provided by eCos GDB stubs/CygMon, but may still allow
eCos to run under third party ROM monitors, using their IO
routines for disagnostics output.