MTK System Error Type

MTK System Error Type

 

There are two typical types of system errors: CPU-triggered system errors and software-triggered system errors. (In fact, I think there is no difference between the two errors. Depend! What is CPU trigger? What is software trigger? Are these two categories meaningful? Is debugging helpful? The answer is no help! After debugging for so many years, I don't think classification is useful. In fact, "Trigger" is better than "detection". One is detected by the CPU, and the other is detected by the software. Whether it is triggered by CPU or software, or by magic blocking or magic blocking !)

 

1. CPU-triggered (detected) System Error

Undefined Instruction Exception (no command defined error)
It means that ARM cannot parse how the current command is executed. In other words, the current command does not belong to the ARM instruction set. But you may wonder how this error may happen? Unless there are bugs in analyticdb, RVCT, and other compilers, such errors cannot be found in the compilation phase. Do these compilers eat rice or even do they not know the commands in the ARM instruction set? Therefore, this error is not a code issue. This error may occur when the program runs and runs in the data area. There are many causes for the flight, such as the function pointer issue, or the partial variable overflow causes the function return address in the stack to be broken.
Software Interrupt Exception
Let's take a look at some interesting things. MTK wrote The following when introducing The SWI exception type: The software interrupt instruction (SWI) is used to enter Supervisor mode, usually to request a special supervisor function.

Could you tell me that SWI is exception from the above section? I can't bear it, or even get crazy. After reading the above explanation, I cannot understand the slightest relationship between SWI and exception. SWI can be interpreted as a software-triggered interrupt, but it is not used in MTK systems. So if the Soft Interrupt is triggered, the program must have been running. At this point, we finally understand why SWI is also an exception.
Pre-fetch Abort Exception
A prefetch instruction error occurs when the CPU reads the instruction from RAM or ROM, the provided address is an Invalid Address (other than RAM and ROM ). It is generally a function pointer issue, or a local variable overflow breaks down the return address of the function in the stack, and so on.
Data Abort Exception
A data error occurs when the data in RAM or ROM is accessed, the provided address is an Invalid Address (an address other than RAM and ROM ). Generally, there is a problem with the Data Pointer.
2. Software-triggered (detected) system errors

Assert Error
The Assert statements embedded by the programmer in the Code include ASSERT (), EXT_ASSERT (), EXT_ASSERT (), and EXT_ASSERT_DUMP () in MTK code ()
Fatal Error
It can be understood as the Assert statement written in the KAL layer. This is some Assert statements that MTK System engineers have buried at the KAL layer. The KAL layer is the Adaptation Layer of the system. Therefore, problems in this layer are generally related to system exceptions. For example, the ctrl buffer is insufficient and the external queue is full.
System Lockup
In this document, the write system is suspended. The younger brother is not talented. debug has not been able to encounter such exceptions for so many years.