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eMMC sudden death research

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By Oranav, Member on 12th January 2013, 05:26 PM
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22nd January 2013, 06:46 AM |#21  
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Re: eMMC sudden death research
As far is it seems right now, it isn't caused by flash wear or anything like that. It seems that it's caused by a bug which is triggered in a very specific case. Then, it causes the device to corrupt its inner structures or its firmware - I'm not sure which one yet.

The specific bug is that they don't check the return value of some function returning a pointer, which may be NULL. It then leads to a NULL pointer dereference which corrupts things.

So, as far as it seems currently, there is no negative effect of using an unpatched kernel (except for the risk of it suddenly dying, of course).


By the way, it's worthy to note that the firmware actually resides on the flash itself. There is a very small boot ROM (which is probably a mask ROM) that loads the firmware out of the NAND device.
Why am I mentioning this? It means that a bug in the firmware may actually corrupt the firmware itself, bricking the device.

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22nd January 2013, 08:31 AM |#22  
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That is awesome research. Assuming that samsung just made a quick "fix" with the new kernels (and it does causing random freezes), Do you think that they can make a proper fix without side effects ?

Assuming they know all about it since SGS2 and it still effects SGS3 this makes samsung a terrible company.
22nd January 2013, 05:42 PM |#23  
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Re: eMMC sudden death research
Quote:
Originally Posted by liamR

Assuming that samsung just made a quick "fix" with the new kernels (and it does causing random freezes), Do you think that they can make a proper fix without side effects ?

Absolutely yes.


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23rd January 2013, 01:43 AM |#24  
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Quote:
Originally Posted by Oranav

Absolutely yes.


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question is, will they be smart enough do actually do it :P
(I'm not talking about their engineers, but their management)
24th January 2013, 01:10 AM |#25  
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@Oranav:
Do you know, if the fix is applied in download mode, too?
I assume that the download mode does _not_ load a kernel or recovery, so the following assumption would be, that in download mode the eMMC is not protected.
Could that be?

BR
Rob
24th January 2013, 02:00 AM |#26  
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Quote:
Originally Posted by Rob2222

@Oranav:
Do you know, if the fix is applied in download mode, too?
I assume that the download mode does _not_ load a kernel or recovery, so the following assumption would be, that in download mode the eMMC is not protected.
Could that be?

BR
Rob

You have to have a kernel. I'm sure it shares the recovery kernel since the recovery kernel is basically a backup/fail-safe kernel.
24th January 2013, 10:56 AM |#27  
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Quote:
Originally Posted by Product F(RED)

You have to have a kernel. I'm sure it shares the recovery kernel since the recovery kernel is basically a backup/fail-safe kernel.

I am not sure about this. From my understanding the (second?) bootloader already has eMMC and display driver. So there are enough parts already initialized to make the eMMC aviable for USB access. No real need to load the kernel for that.

If download mode would need kernel/recovery, it would not be aviable if you flash a wrong kernel/recovery. And if I remember right I've seen wrong kernel and wrong recovery flashs got repaired by just flashing the correct kernel/recovery, so download mode was still working.

BR
Rob
24th January 2013, 01:12 PM |#28  
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Re: eMMC sudden death research
Quote:
Originally Posted by Rob2222

I am not sure about this. From my understanding the (second?) bootloader already has eMMC and display driver. So there are enough parts already initialized to make the eMMC aviable for USB access. No real need to load the kernel for that.

If download mode would need kernel/recovery, it would not be aviable if you flash a wrong kernel/recovery. And if I remember right I've seen wrong kernel and wrong recovery flashs got repaired by just flashing the correct kernel/recovery, so download mode was still working.

BR
Rob

You could be right but I know that recovery mode has its own separate kernel. That's why I thought maybe download mode shared it.

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24th January 2013, 08:43 PM |#29  
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Re: eMMC sudden death research
Download mode has nothing in common with the recovery partition. It is implemented in sboot (the device's bootloader).
It has its own implementation of hardware drivers. If it doesn't patch the eMMC RAM, then it isn't safe!

However, I haven't checked it enough yet to conclude whether it's safe or not. Right now, I'd recommend anyone to avoid flashing via download mode. Recovery and Mobile Odin (or just dd) are good enough.

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25th January 2013, 11:46 AM |#30  
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Quote:
Originally Posted by Oranav

Download mode has nothing in common with the recovery partition. It is implemented in sboot (the device's bootloader).
It has its own implementation of hardware drivers. If it doesn't patch the eMMC RAM, then it isn't safe!

However, I haven't checked it enough yet to conclude whether it's safe or not. Right now, I'd recommend anyone to avoid flashing via download mode. Recovery and Mobile Odin (or just dd) are good enough.

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Makes sense into why they upgraded the bootloader with LLA then, the increased modification detection would be just a side-effect of a newer bootloader version which already had heightened warranty enforcements on the 9305 and the Note 2's.
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