Clarify STM32F103x8 Flashsize handling.

Should finally fix #471.

src/platforms/stlink/Flashsize_F103

@@ -20,34 +20,31 @@ This flash may have been tested bad, or not have been tested at all,
 or, in the best case, was tested good but market requirements made STM sell
 it as F103C8.
 
-Ignoring the chip marking and using an F103C8 blindly as a F103Cb is done
-already with few problems on many china boards (e.g. blue pill). Probably
-this second approach will work for many of the older STLinks.
-
-dfu-util cares for the size and refuses to programm above the announced size:
- > dfu-util -S E4D078EA -s 0x08002000:leave -D blackmagic.bin
- dfu-util 0.9
- ...
- dfu-util: Last page at 0x0801093f is not writeable
+Ignoring the chip marking and using an F103C8 blindly as a F103CB is done
+already with no known problems on many STM board and china boards (e.g. blue
+pill) with genuine STM32. China stlinks clones with a GD32F103x8 will
+probably not work. Best is to get new genuine ST hardware. The
+STLINK-Vmini is < 10 $ without VAT or to resolder a genuine
+STM32F103CB chip. Think also about using the pc-hosted pc-stlinkv2
+platform on stlinks with revent firmware.
 
 Flash above the announced size with recent bootloader/BMP:
 ==========================================================
-script/stm32_mem.py does not care for the announced size:
+
+Use either the provided python tool, as script/stm32_mem.py
+does not care for the announced size and verifies:
+
  > ../scripts/stm32_mem.py blackmagic.bin
- ...
- USB Device Firmware Upgrade - Host Utility -- version 1.2
- ...
- Programming memory at 0x08010800
- All operations complete!
 
-Get length of binary
-  > ls -l blackmagic.bin
- -rwxr-xr-x 1 bon users 59712 21. Sep 22:47 blackmagic.bin
-Actual file size may differ!
+or compile and use the upgrade executable.
 
-Upload binary from flash with the exact size
-  > dfu-util -s 0x08002000:leave:force:59712 -U blackmagic.bin.1
+> cd upgrade
+> make (PROBE_HOST=...)
+> ./blackmagic_upgrade
 
-Compare
-  > diff blackmagic.bin*
-No differences should get reported!
+To long to read
+===============
+Use the BMP provided upgrade tools:
+- scripts/stm32_mem.py
+- Compiled upgrade tool in upgrade
+Only if mismatch is reported, think further.

upgrade/Makefile

@@ -36,7 +36,7 @@ endif
 
 bindata.o: $(PROBE_HOST).d
 
-$(PROBE_HOST).d: ../src/blackmagic.bin
+$(PROBE_HOST).d: $(wildcard ../src/blackmagic.bin)
 	-rm *.d
 	make -C ../src $0 clean
 	make -C ../src $0