Rockbox Development > New Ports
Sandisk Sansa e200 v2
saratoga:
--- Quote from: pgs on March 16, 2008, 07:23:09 AM ---
--- Quote from: saratoga on March 15, 2008, 11:01:34 PM ---
Yes but if the firmware you flash does not work, none of that will matter since the system will crash as soon as it boots. Â This is why you need a way to recover from bad flashes.
--- End quote ---
There is one assumption that maybe was not clear: the MSC mode is in the ROM (Read Only Memory), not in the flash (or it is in the boot loader of the flash, which can be protected).
So, as soon as the device is attached to a PC, it goes in MSC (if enabled) and this will always work, no matter what firmware it has.
This is similar to the (not so new) BIOS recovery feature of PCs, where, even in case of bad flashing, there is a part of the BIOS untouched, which can boot and reprogram the flash by its own.
If the flashing is gone bad, the device will be anyway able to go in MSC and reprogram the flash, since this mode is non-modifiable.
In other words, the very first boot manager is in ROM and it always has the chance to start the firmware or go into MSC mode, no matter how bad is the firmware, and later re-flash or re-start the firmware.
They _could_ have implemented this way, hopefully they did.
pgs
--- End quote ---
Has anyone reported being able to get into UMS mode without booting the device? I don't recall anyone saying so, which is why I tend to think its not possible to do that on the V2 (at least without some sort of hardware modding or unknown recovery mode).
pgs:
--- Quote from: saratoga on March 16, 2008, 02:49:44 PM ---Has anyone reported being able to get into UMS mode without booting the device? I don't recall anyone saying so, which is why I tend to think its not possible to do that on the V2 (at least without some sort of hardware modding or unknown recovery mode).
--- End quote ---
It _could_ be that MSC mode, or UMS mode, is always active _without_ booting the firmware.
How do you know if it is the firmware in flash running or the one in ROM?
You can't, so "booting" does not mean the firmware in flash is running, it just means the device is executing some starting code, but we do not know where this code is coming from.
This is the same as saying: how can you go in recovery mode without booting the firmware?
You can, since you do not boot the firmware, recovery mode happens before, same goes here.
When a key combination is pressed, who is reading the keys? If the firmware does not work, the machine did not boot, how could be the CPU reads the keypad? The CPU executes ROM code, that is it.
It _could_ be that the recovery mode _is_ the MSC mode.
I mean by this, _active_ MSC mode, i.e. MSC mode while connected to a PC. Like any simple mp3 player does.
How can I explain it more clearly?
Let me try again...
The ARM has a ROM, with some boot code. This is the code executed at power up (or reset), this goes in the booting phase. That is, the device always boots. This code is _not_ flashable. This code handle the MSC mode, _before_ the firmware starts.
_If_ they implemented this way, the MSC mode will always be available, it will be always possible to copy a new firmware to the device and, consequently, to update it.
Note that, when in MSC mode, connected to a PC, you cannot play songs or do anything with the device, like the firmware is not active...
Anyway, this are just hypothesis, without a test, there is not much to say more...
This means that, until someone bricks a device and recovers (or not) by MSC, we will never know for sure.
Any volunteers here? :-)
pgs
fed:
Have you tried to ask Sansa if your hypothesis is correct?
pgs:
--- Quote from: fed on March 16, 2008, 08:25:46 PM ---Have you tried to ask Sansa if your hypothesis is correct?
--- End quote ---
Well, actually I was deriving the hypothesis from the comments of people asking the "recovery" question to Sandisk.
It seems the answer was always: "do this and that and you'll be in MSC mode", so I came to the conclusion that the device, connected to a PC, in MSC mode, _is_ in recovery mode.
Anyway, I sent an email to the Sandisk support, time ago, with a similar question and I'm still waiting the answer, so...
pgs
eXomaniac:
As is also own a Sansa 280 v2 and want to see Rockbox on it, i would like to know what exactly should be tested / done now to get this port forwards.
Is there any safe way to test this recovery mode ?
One thing i know ( dont know if this actually was told) is that to upgrade the firmware you have to plugin the sansa to you pc so it loads in MSC mode and then the firmware is being upgraded. After this you plug out, and after reboot you see that the player himself is updating and ready for use.
Perhaps it helps to know... as i dont know much about this, for me it sounds logically to use this as a recovery mode / firmware mode.
I want to help, tell me how ;)
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