The semantics of "-work-area-virt 0" (or phys) changed with
the patch to require specifying physical or virtrual work
area addresses. Specifying zero was previously a NOP. Now
it means that address zero is valid.
This patch addresses three related issues:
- MMU-less processors should never specify work-area-virt;
remove those specifications. Such processors include
ARM7TDMI, Cortex-M3, and ARM966.
- MMU-equipped processors *can* specify work-area-virt...
but zero won't be appropriate, except in mischievous
contexts (which hide null pointer exceptions).
Remove those specs from those processors too. If any of
those mappings is valid, someone will need to submit a
patch adding it ... along with a comment saying what OS
provides the mapping, and in which context. Example,
say "works with Linux 2.6.30+, in kernel mode". (Note
that ARM Linux doesn't map kernel memory to zero ...)
- Clarify docs on that "-virt" and other work area stuff.
Seems to me work-area-virt is quite problematic; not every
operating system provides such static mappings; if they do,
they're not in every MMU context...
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Prerequisites:
The users of OpenOCD as well as computer programs interacting with OpenOCD are expecting that certain commands
do the same thing across all the targets.
Rules to follow when writing scripts:
1. The configuration script should be defined such as , for example, the following sequences are working:
reset
flash info <bank>
and
reset
flash erase_address <start> <len>
and
reset init
load
In most cases this can be accomplished by specifying the default startup mode as reset_init (target command
in the configuration file).
2. If the target is correctly configured, flash must be writable without any other helper commands. It is
assumed that all write-protect mechanisms should be disabled.
3. The configuration scripts should be defined such as the binary that was written to flash verifies
(turn off remapping, checksums, etc...)
flash write_image [file] <parameters>
verify_image [file] <parameters>
4. jtag_khz sets the maximum speed (or alternatively RCLK). If invoked
multiple times only the last setting is used.
interface/xxx.cfg files are always executed *before* target/xxx.cfg
files, so any jtag_khz in interface/xxx.cfg will be overridden by
target/xxx.cfg. jtag_khz in interface/xxx.cfg would then, effectively,
set the default JTAG speed.
Note that a target/xxx.cfg file can invoke another target/yyy.cfg file,
so one can create target subtype configurations where e.g. only
amount of DRAM, oscillator speeds differ and having a single
config file for the default/common settings.
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