FreeCalypso > hg > freecalypso-tools

comparison doc/Flash-programming @ 677:3a41d69e8104

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
doc/Flash-programming: added section about discontiguous m0 images
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 08 Mar 2020 22:53:30 +0000
parents b6b8307d195b
children a7496a1e0df7
comparison
equal deleted inserted replaced
676:b6b8307d195b 677:3a41d69e8104
75 sectors into which new bits will be programmed, then programs the new bits. 75 sectors into which new bits will be programmed, then programs the new bits.
76 Thus a third equally good way to flash a new FreeCalypso fw release into a 76 Thus a third equally good way to flash a new FreeCalypso fw release into a
77 target such as FCDEV3B or GTA02 is to execute 77 target such as FCDEV3B or GTA02 is to execute
78 'flash e-program-bin 0 fwimage.bin' - but don't *ever* do it on a Mot C1xx 78 'flash e-program-bin 0 fwimage.bin' - but don't *ever* do it on a Mot C1xx
79 phone! 79 phone!
80
81 Discontiguous m0 fw images with large gaps
82 ==========================================
83
84 One sometimes-advantage of S-record-based formats over straight binary is that
85 they can have discontiguous filled regions with gaps in between them; all m0 fw
86 images produced by TI's TCS211 build system have some gaps in them. In our
87 current FC Magnetite firmwares these gaps have been reduced to less than 16384
88 bytes in total, reducing the wasted disk space and image transfer time to
89 sufficiently insignificant if these m0 images are converted to straight binary
90 with mokosrec2bin and then flashed as binary as we've been doing. For
91 comparison, in Openmoko's classic mokoN firmwares (almost TI's original version
92 of the memory map) the first flash sector of 65536 bytes had only 5072 bytes of
93 image payload programmed into it, thus indirect programming via mokosrec2bin
94 followed by flash program-bin meant sending just over 60k filler 0xFF bytes to
95 be flashed - becomes noticeable at 115200 baud.
96
97 But these gaps were even bigger in TI's classic firmwares (and many vendor
98 firmwares) built for 8 MiB or 16 MiB flash chips with TI's classic memory map.
99 They have two code regions: one region is exactly 4 MiB in size but is placed
100 not quite at the beginning, thus spilling past the chip midpoint, and the other
101 region starts where the first 4 MiB region ends, going to the end of the flash
102 chip or to the beginning of the area reserved for FFS. The way TI's linker
103 works results in the first of these two program regions being not quite full
104 before bits start getting thrown into the second one, thus the resulting m0
105 image can easily have a gap of a megabyte or more between the two regions.
106 TI's own FLUID handles such discontiguous images with no sweat, but our
107 fc-loadtool has gained matching capability only as of fc-host-tools-r13 with
108 our new e-program-m0 command. And yes, it is smart enough to avoid needlessly
109 erasing sectors in the big gap, just like FLUID.
80 110
81 Flash backup and restore 111 Flash backup and restore
82 ======================== 112 ========================
83 113
84 A completely different paradigm takes place on alien targets such as Motorola 114 A completely different paradigm takes place on alien targets such as Motorola