Why flashing smartphone may lead to "Kirpichniy"?

Maybe in the case of UEFI is somehow harder, but before PC was like this: BIOS reads the MBR and transfers control to (what is on disk).

On a disk - the bytes to insert the disk in another computer or just connecting it bus to another device, you can for sure count. And then also recover.

Well, in BIOS there are some settings. Them - Yes, you can screw up. But I think even they were kept at the expense of the returned batteries. Well, or Capability, or whatever.

But "atypical" PC - I, the programmer, hard to say as of yet.

What else in smartphones? We there pereproshivka that is the skiff?

This is the first question. And second - why is no one known to me the smartphone is not behaving as a USB flash drive when in the off state, I connect it to PC? More precisely, this is due to technology or marketing? (By the way, a year ago I asked this question on 4PDA, there were surprised with my question and difficult to answer.)

P. S. And what a difference on this issue UEFI from BIOS? There SecureBoot/etc., there is a way to completely prevent the "reset"...

P. P. S. don't embarrass me, pzhl, for this question. I simply do not know. But in the course of something else :-)

Thank you!
June 14th 19 at 20:37
7 answers
June 14th 19 at 20:39
Solution
Because if you will not be sewn boot loader from another model - it may not earn or earn is not correct. Depends on the contents of firmware and mode firmware - ie from konretno model(whatever is implemented). Modern models are difficult to kill IOS.
Don't drive like a flash drive - most likely due to marketing, as it at least runs the bootloader to show the percent of charge - just not in this program to broadcast the contents of the drive in USB-HDD. And of course the safety of the loader is not able to verify the legality(there is no such program).
Why did so - because it's easier.
Thanks for the reply!

That is, there are two independent areas of memory?

First, apparently, is called the bootloader and it loads the second. And if it does not overwrite, do not atypicals. But bootloader imposes restrictions on flashing, depending on the appetites of the manufacturer, so you may have to reflash and it (although... how?) Am I right? - Elda_Mertz commented on June 14th 19 at 20:42
Just all use Uboot and he is the most can show the percent of charge. Except in the second boot loader on the flash drive yet there is a loader built into the processor - it usually works in FACTORY MODE - using common circuitry, it has direct access to any memory and can only write and read, with the screen and the periphery does not work, you need to download the firmware at the factory.

On the hard drive 2 partition at least boot,kernel,initrd,system,data usually are added to them 1 or 2 recovery partition (kernel,initrd or initrd only). In modern smartphones in about 10 sections (as the marketers specify the size of the drives installed).

theme is great, just not to describe, and I don't know everything. - Iliana_Strosi commented on June 14th 19 at 20:45
so if there is a "boot loader built into the processor" - how can something atypical? - Elda_Mertz commented on June 14th 19 at 20:48
the fact that you may need JTAG and diagnostic interface to communicate with this bootloader and push the correct firmware.
Because USB its not enough =)))
This is about how to require a bootblock'BIOS support Ethernet, USB mouse, and all this with a graphical interface - Jarred.Gleason51 commented on June 14th 19 at 20:51
OK , what is JTAG I also can imagine =) That is JTAG/etc. can be guaranteed to recipicate? And with JTAG, this story will not remain magic poluostrovnaya parts? =) - Elda_Mertz commented on June 14th 19 at 20:54
well, in some places up to it physically you will reach hell. There are such devices. - Jarred.Gleason51 commented on June 14th 19 at 20:57
FU , thank God. Explain. I worked with STM32F4 Discovery, and... well, a Little in the subject. But to understand how it can be "fully atypicity", I was not able to understand. It is now clear - "if you have no programmer" =) Thank you! - Elda_Mertz commented on June 14th 19 at 21:00
not, well, you can still physically damage is not very good EEPROM frequent erasures/records. Curve Chinese flash eMMC bring to this in principle, really. - Jarred.Gleason51 commented on June 14th 19 at 21:03
The only option that I would understand - "the self-destruction of marketing considerations." If the internal programmer is reprogramming feels wrong, it goes into a special mode - not working. Until electric camdestroy (or it just the ROM.). I feared so... - Elda_Mertz commented on June 14th 19 at 21:06
well not at such a low level.
Usually it happens hard, checksum and/or a digital signature already bootloader'ohms and the inability to load something unsigned.
Or harder, with full encryption key contained in bootloader'e and downloadable firmware. The key is not the same = all. All sorts of tokenization, HTC S-On and Samsung KNOX work.
Read about KNOX, after the Apple paranoia is probably the following from existing similar solutions. - Jarred.Gleason51 commented on June 14th 19 at 21:09
well Yes, but with this story because bootloader ROM (no JTAG)? And he will be guaranteed to work, no? - Elda_Mertz commented on June 14th 19 at 21:12
in some places not ROM. And for example "matryoshka" with the ability to flash the subject H. For example, if you have the correct certificate or key developer. But some higher-level software already ROM. And purely in theory possible option "with the key on the recording and not having the correct image flashed an unknown crap and now the checksum does not match or the encryption key is lost". - Jarred.Gleason51 commented on June 14th 19 at 21:15
clearly , thanks! When KNOX read. In UEFI SecureBoot similar? - Elda_Mertz commented on June 14th 19 at 21:18
similar mechanism for the objectives and principle, but different implementation. - Jarred.Gleason51 commented on June 14th 19 at 21:21
June 14th 19 at 20:41
If you alter the BIOS of the computer on all the dregs, he will not run.

In General, on most modern phones have a firmware recovery mode - Fastboot on Xiaomi, Samsung on Download Mode, special mode MTK the percent. This mode provides the minimum functionality to upload new firmware. But if this loader to flash on the incompatible version, just the phone nothing will load. Any mode produces an error. Insert external media and boot from it it is impossible, he is simply not able.

That to USB to phones it software, the operating system decides how and what is available via USB. In the off state, the percent MTK USB connection transfers the Prots to the boot regime, he for a moment is defined as the COM port.

Another problem with the "USB key" is that on the Android phones internal memory is formatted ext4 and Windows this FS does not understand. In poor condition, you can enable MTP mode for more complex interaction. Mode minimum functionality, not even wood on the eMMC (UFS), not to connect it straight to USB. All this is difficult
Thanks for the reply!

But if "special mode MTK the percent not to flash", then nothing will be broken?

And about the "USB software" is technically justified, or marketing? In a flash drive it's all there, it's small (not counting the plug). What's the problem?

And through contacts any (a La GPIO? no, JTAG) can access Flash to get hold of? - Elda_Mertz commented on June 14th 19 at 20:44
that flash drive hardware (controller with primitive firmware, or even the hardcore and the FPGA, were the first drives on USB 1.1), implements the USB Mass Storage mode. And the phone's CPU is a program one of the modes.
Technically, nothing prevents to implement it. The processor will thrash on some is not IDLE-the new clock frequency, driving the same branch of code that is responsible for USB Mass Storage.
Imagine a modern car in the Parking lot, engine off, doors closed, the cabin is unoccupied, the alarm - and You want to be forgotten in salon the cat was able to turn the music on or heated seats. Something like that.

If you really want USB Mass Storage without running the firmware - it is in many Bootloader'Oh and Recovery, for example TWRP.

If you compare with the BIOS - it BIOS with mouse, built-in file Manager and a handful of their drivers. - Iliana_Strosi commented on June 14th 19 at 20:47
thank you! Yes, now all aware... - Elda_Mertz commented on June 14th 19 at 20:50
June 14th 19 at 20:43
Imagine yourself as a doctor. You need to transplant the brain itself. You cut open the skull, cut a artery and... I forgot who You are, where You are and what you intend to do.

So it is with computers. They quickly overwrite its program, to avoid "Kirpichny", that is, the loss of some part of the program and the impossibility of reading it. And if suddenly something goes not so, will, as in the case with the doctor.
June 14th 19 at 20:45
June 14th 19 at 20:47
June 14th 19 at 20:49
Smarta have no BIOS. It is the role of the bootloader. If to sew up in the smart loader from another model or even from another phone - well, phone time... and will not boot - the same effect as if into a computer to sew BIOS from another model.
June 14th 19 at 20:51
Why flashing smartphone may lead to "Kirpichniy"?
Everything is exactly the same as in the case of the computer.

If you erase the boot record on the system disk of your computer "atypicity" and bring it to life can only be a specialist from the service.

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