Analyzing trap root cause

TINs (Trap Identification Number) are used for detailed analysis of the trap root cause in aid of data in DSTR, DATR, and DEADD registers. Traps are divided into 8 classes, each with similar types of traps. Each class has a further division to identify what happened in detail. This division is based on specific TINs. The corresponding description is in chapter Trap descriptions.

DMI Trap Generation (DMI = Data Memory Interface) can be found in Aurix target specification chapter 5.3.6.4.4 [2]. Register description of DSTR, DATR, and DEADD in the same chapter below. These three registers are used to aid with the localization of faults. DSTR meaning is to inform about which synchronous error caused a trap. DATR meaning is to inform about which asynchronous error caused a trap. And the value of DEADD is an address that tells detailed information about the fault. The DEADD register contents are only valid when either the DATR or DSTR register is non-zero.

For Asynchronous traps, PXROS-HR does not read the DATR register, and the user always has to read the DATR register to get the reason of the trap.

For example, if a task tries to write at address 0x8 and its memory protection unit is not set for that address, this write (store instruction) causes a trap. DSTR is updated, and the MPE bit is set. In the DEADD register is the value of the address where the task tried to write (0x8).

Tab. 1. Information contained in 'DSTR' register
Bit	Bit Name	Description
SRE	Scratch Range Error	Data access to data scratch memory region outside of physically implemented memory
LBE	Load Bus Error	Data load from bus causing error
CRE	Cache Refill Error	Bus error during cache refill
DTME	DTAG MSIST Error	Access to memory mapped DTAG range outside of physically implemented memory
LOE	Load Overlay Error	Load to invalid overlay address
SDE	Segment Difference Error	Load or store access where base address is in different segment to access address
SCE	Segment Crossing Error	Load or store access across segment boundary
CAC	CSFR Access Error	Load or store to local CSFR space
MPE	Memory Protection Error	Data access violating memory protection.
CLE	Context Location Error	Context operation to invalid location
ALN	Alignment Error	Data access causing alignment error

Tab. 2. Information contained in 'DATR' register
Bit	Bit Name
SBE	Store Bus Error
CWE	Cache Writeback Error
CFE	Cache Flush Error
SOE	Store Overlay Error