From 5970fcfa8aaf8278dba97e088e591faf99282326 Mon Sep 17 00:00:00 2001
From: Daniel Stenberg <daniel@haxx.se>
Date: Mon, 21 Jul 2003 12:04:30 +0000
Subject: Jörg Hohensohn's "howto flash" document, webified
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+#define _PAGE_ Rockbox in Flash - FAQ and User Manual
+#include "head.t"
+<p>
+by Jörg Hohensohn aka [IDC]Dragon
+<p>
+1. What is this about?<br>
+2. How is it working?<br>
+3. Is it dangerous?<br>
+4. Will it work for me?<br>
+5. How do I flash the firmware?<br>
+6. How do I bring in a current / my personal build of Rockbox?<br>
+7. Known issues, limitations<br>
+
+<h1>1. What is this about?</h1>
+<p>
+This package contains tools to update the flash content of Archos Jukebox
+Recorder / FM.
+<p>
+Some terminology I'm gonna use in the following:
+Firmware means the flash ROM content as a whole.
+Image means one operating software started from there.
+By reprogramming the firmware we can boot much faster. Archos has a pathetic
+boot loader, versus the boot time for rockbox is much faster than the disk
+spinup, in fact it has to wait for the disk. Your boot time will be as quick as
+a disk spinup. In my case, that's 3 seconds from powerup until resuming
+playback.
+
+<h1>2. How is it working?</h2>
+<p>
+The replaced firmware will host a bootloader and 2 images. I use data
+compression to make this possible. The first is the "permanent" backup, not to
+be changed any more. The second is the default one to be started, the first is
+only used when you hold the F1 key during start. Like supplied here, the first
+image is the original Archos firmware, the second is a current build of
+Rockbox. This second image is meant to be reprogrammed, it can contain anything
+you like, if you prefer, you can program the Archos firmware to there, too.
+<p>
+I supply two programming tools:
+<ul>
+<li> The first one is called "firmware_flash.rock" and is used to program the
+whole flash with a new content. You can also use it to revert back to the
+original firmware you've hopefully backup-ed. In the ideal case, you'll need
+this tool only once. You can view this as "formatting" the flash with the
+desired image structure.
+<li> The second one is called "rockbox_flash.rock" and is used to reprogram only
+the second image. It won't touch any other byte, should be safe to fool around
+with. If the programmed firmware is inoperational, you can still use the F1
+start with the Archos firmware and Rockbox booted from disk to try better.
+</ul>
+<p>
+I will provide more technical details in the future, as well as my non-user
+tools. There's an authoring tool which composed the firmware file with the
+bootloader and the 2 images, the bootloader project, the plugin sources, and
+the tools for the UART boot feature: a monitor program for the box and a PC
+tool to drive it.
+
+<h1>3. Is it dangerous?</h3>
+<p>
+Yes, certainly, like programming a mainboard BIOS, CD/DVD drive firmware,
+mobile phone, etc. If the power fails, your chip breaks while programming or
+most of all the programming software malfunctions, you'll have a dead box. And
+I take no responsibility of any kind, you do that at your own risk. However, I
+tried as carefully as possible to bulletproof this code. The new firmware file
+is completely read before it starts programming, there are a lot of sanity
+checks. If any fails, it will not program. Before releasing this, I have
+checked the flow with exactly these files supplied here, starting from the
+original firmware in flash. It worked reliably for me, there's no reason why
+such low level code should behave different on your box.
+<p>
+There's one ultimate safety net to bring back boxes with even completely
+garbled flash content: the UART boot mod, which in turn requires the serial
+mod. It can bring the dead back to life, with that it's possible to reflash
+completely from the outside, even if the flash is completely erased. I used
+that during development, else Rockbox in flash wouldn't have been possible.
+Most of the developing effort went into this tooling. So people skilled to do
+these mods don't need to worry. The others may feel unpleasant using the first
+tool for reflashing the firmware.
+<p>
+To comfort you a bit again: The flash tools are stable since a while. I use
+them a lot and quite careless meanwhile, even reflashed while playing. However,
+I don't generally recommend that.  ;-)
+<p>
+About the safety of operation: Since we have dual boot, you're not giving up
+the Archos firmware. It's still there when you hold F1 during startup. So even
+if Rockbox from flash is not 100% stable for everyone, you can still use the
+box, reflash the second image with an updated Rockbox copy, etc.
+<p>
+The flash chip being used by Archos is specified for 100,000 cycles (in words:
+one hundred thousand), so you don't need to worry about that wearing out.
+
+<h1>4. Will it work for me?</h1>
+<p>
+You need two things:
+<ul>
+<li> The first is a Recorder or FM model. Be sure you're using the correct
+package, Recorder and FM are different! In principle, the technology works for
+the Player models, too. It's just that no work has been spent on this
+(developers welcome).
+
+<li> Second, you need an in-circuit programmable flash. Chances are about 85%
+that you have, but Archos also used an older flash chip which can't do the
+trick.  You can find out via Rockbox debug menu, entry Hardware Info. If the
+flash info gives you question marks, you're out of luck. The only chance then
+is to solder in the right chip (SST39VF020), at best with the firmware already
+in. If the chip is blank, you'll need the UART boot mod as well.
+</ul>
+
+<h1>5. How do I flash the firmware?</h1>
+<p>
+I'm using the new plugin feature to run the flasher code. There's not really a
+wrong path to take, however here's a suggested step by step procedure:
+<ul>
+<li> copy 3 files of <a href="http://joerg.hohensohn.bei.t-online.de/archos/">this package</a> to the root directory of your box:<ol>
+  <li> ajbrec.ajz (the version of Rockbox we're going to use and have in the
+firmware file)<br>
+  <li> firmware_flash.rock (the plugin for this job)<br>
+  <li> firmware_rec.bin or firmware_fm.bin (the complete firmware for your model,
+with my bootloader and the two images)
+ </ol>
+<li> Restart the box so that the new ajbrec.ajz gets started.
+
+<li> Enter the debug menu and select the hardware info screen. Check you flash
+IDs (bottom line), and please make a note about your hardware mask value
+(second line). The latter is just for my curiosity, not needed for the
+flow. If the flash info shows question marks, you can stop here, sorry.
+
+<li> Backup the current firmware, using the first option of the debug menu
+(Dump ROM contents). This creates 2 files in the root directory, which you may
+not immediately see in the Rockbox browser. The 256kB-sized
+"internal_rom_2000000-203FFFF.bin" one is your present firmware. Back it up to
+your PC.
+
+<li> (optional) While you're in this Rockbox version, I recommend to give it a
+test and play around with it, this version is identical to the one about to be
+programmed. Make sure that especially USB access and Rolo works. When done,
+restart again to have a fresh start and to be back in this Rockbox version.
+
+<li> Use the F2 settings to configure seeing all files within the browser.
+
+<li> Connect the charger and make sure your batteries are also in good
+shape. I'm just being paranoid here, it's not that flashing needs more power.
+
+<li> Run the "firmware_flash.rock" plugin. It again tells you about your flash
+and the file it's gonna program. After F1 it checks the file. Your hardware
+mask value will be kept, it won't overwrite it. Hitting F2 gives you a big
+warning.  If I still didn't manage to scare you off, you can hit F3 to
+actually program and verify. The programming takes just a few seconds.
+
+<li> In the unlikely event that the programming should give you any error,
+don't switch off the box! Otherwise you'll have seen it working for the last
+time.  While Rockbox is still in DRAM and operational, we could upgrade the
+plugin via USB and try again. If you switch it off, it's gone.
+
+<li> When the programming is done, rename the "ajbrec.ajz" file to
+ajbrec.ajz_" or so. Pressing On+Play can do it, or the PC via USB. This is a
+nice trick to make only the Archos firmware find and load it, versus Rockbox
+looks for the exact filename. Since Rockbox is up to date, there's no point in
+having it loading this on startup.
+
+<li> Unplug the charger, restart the box and hopefully be in Rockbox straight
+away! You should delete "firmware_flash.rock" then, to avoid your little
+brother playing with that. Again, pressing On+Play can do it, or your PC. You
+can also delete the ".bin" files.
+
+<li> Try starting again, this time holding F1 while pressing On. It should
+boot the Archos firmware, which then loads rockbox from disk. In fact, even
+the Archos firmware comes up quicker, because their loader is replaced by
+mine.
+
+</ul>
+
+When for any reason you'd like to revert to the original firmware, you can do
+like above, but copy and rename your backup to be "firmware_rec.bin" on the
+box this time. Keep the Rockbox copy and the plugins of this package for that
+job, because that's the one it was tested with.
+
+<h1>6. How do I bring in a current / my personal build of Rockbox?</h1>
+<p>
+The second image is the working copy, the "rockbox_flash.rock" plugin from this
+package reprograms it. I suggest to place the plugin to where you keep the
+others, "/.rockbox/rocks/". The plugin needs to be consistant with the Rockbox
+plugin API version, otherwise it will detect mismatch and won't run.
+<p>
+It currently requires an exotic input, a UCL-compressed image, because that's
+my internal format. UCL is a nice open-source compression library I found and
+use. The decompression is very fast and less than a page of C-code. The
+efficiency is even better than Zip with maximum compression, cooks it down to
+about 58% of the original size. For details on UCL, see:
+http://www.oberhumer.com/opensource/ucl/
+<p>
+Linux users will have to download it from there and compile it, for Win32 and
+Cygwin I can do that, so the executables are in the package. The sample program
+from that download is called "uclpack". We'll use that to compress
+"rockbox.bin" which is the result of the compilation. If flashing becomes very
+popular, this could be a part of the build process.
+<p>
+Don't flash any "old" builds which don't have the latest coldstart ability I
+brought into cvs these days. They won't boot. These instructions refer to
+builds from cvs state 2003-07-10 on.
+<p>
+Here are the steps:
+<ul>
+<li> If you start from a .ajz file, you'll need to descramble it first into
+"rockbox.bin", by using "descramble ajbrec.ajz rockbox.bin". IMPORTANT: For an
+FM, the command is different, use "descramble -fm ajbrec.ajz rockbox.bin"!
+Otherwise the image won't be functional.
+
+<li> Compress the image using uclpack, algorithm 2e (the most efficient, and
+the only one supported by the bootloader), with maximum compression, by typing
+"uclpack --2e --best rockbox.bin rockbox.ucl". You can make a batch file for
+this and the above step, if you like.
+
+<li> Copy the resulting file to the root directory of your box.
+
+<li> Start the "rockbox_flash.rock" plugin. It's a bit similar to the other
+one, but I made it different to make the user aware. It tells you the flash
+size and the starting position (so you can calculate how much is left). After
+pressing F1 it will check the file, available size, etc. With F2 it's being
+programmed, no need for warning this time. If it goes wrong, you'll still have
+the permanent image.
+
+<li> When done, you can restart the box and hopefully your new Rockbox image.
+
+</ul>
+
+A more luxurious version of the plugin could do the descrambling and
+compression by itself, but that's hard to do because a plugin is very limited
+with memory (32kB for code and data). Currently I'm doing one flash sector
+(4096 bytes) at a time. Don't know how slow the compression algorithm would be
+on the box, that's the strenuous part.
+
+<h1>7. Known issues, limitations</h1>
+<p>
+The latest ATA init fixes seemed to have solved early adopter's problems.
+However, the wait for the harddisk is longer, you're unlikely to reach the 3
+seconds boot time. I hope it will improve one day again. If there should still
+be ATA errors on startup, use F1-On for the Archos image. Then you can either
+reprogram the original firmware from your backup, or live with F1-On until a
+better Rockbox build resolves it, or program the Archos software in the second
+image, too.
+
+<p>
+Loading the original Archos firmware via rolo may hang, if Rockbox is started
+from flash. This is some initialization problem which I hope to fix, rolo-ing
+Rockbox versions works OK. If you feel homesick, hold F1 during powerup.
+
+<p>
+The behavior with plugged charger differs from original: the box starts when
+you plug it in (no charging screen). You can't power it off while the charger
+is plugged in, instead it kindof restarts in an odd way, can give ATA init
+errors in this case. This is not harmful, sortof reminds to unplug before
+powering off.
+
+<p>
+Rockbox currently insists on starting the HD before doing anything useful.
+This can be a problem if the batteries are deeply discharged and too weak to
+power up the HD, preventing rockbox to start up and charge them. Current
+workaround is to hold F1 while plugging in, this gives the Archos charging
+screen.
+
+#include "foot.t"
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