Solutions to Common Warnings and Error Messages of KEIL C Compiler

If the memory type is not specified for the function's independent variables, local variables, and global variable declarations, the memory mode will become the default memory type. If
the variable of the memory type is specified, the memory mode will be ignored and the specified memory type will be the main one.
    
SMALL mode:
    All variables, local variables, or global variables in the small mode are specified to exist in the address range of 0-0x7F of the internal RAM. This mode is like
defining all variables as data type memory.
    
COMPACT mode:
    All variables in the compressed mode will be assigned to the external data memory with an address range of 0-0xFF. This mode is like defining all variables
as pdata type memory.
    
LARGE mode:
    All variables in the large mode will be assigned to the external data memory with an address range of 0-0xFFFF. This mode is like defining all variables
as xdata type memory.

Re: Bank Switch cannot compile message

[QUOTE]The original poster is Vic 

1.*** WARNING L15: MULTIPLE CALL TO SEGMENT 
SEGMENT: ?PR?SD_INITIALIZE?DRVSD 
CALLER1: ?C_C51STARTUP 
CALLER2: ?PR?TIMER0_ISR?INTERRUPT 


This means that the SD_INITIALIZE function is 
called by C_C51STARTUP and the interrupt service function TIMER0_ISR. 
What problems will this cause?  If the TIMER0_ISR interrupt occurs when SD_INITIALIZE is called, there will be a reentrant problem if SD_INITIALIZE 
is called again  . Keil C51 The local variables of general functions are placed in the same place, so they cannot be  reentrant. If the program guarantees that such a situation will not occur (for example, disable interrupt before calling  ), you can ignore this warning.  2.*** ERROR L107: ADDRESS SPACE OVERFLOW  SPACE: XDATA  SEGMENT: ?XD?DRVMS  LENGTH: 0515H  XDATA is used too much! Lose weight!  3.*** WARNING L17: INTERRUPT FUNCTION IN BANKS NOT ALLOWED  SYMBOL: INT0_ISR  SPACE: BANK0  cannot put interrupt function in bank area  4.*** WARNING L4: DATA SPACE MEMORY OVERLAP  FROM: 003FH  TO: 0050H  Some data areas are shared by two devices  5.*** ERROR L105: PUBLIC REFERS TO IGNORED SEGMENT  SYMBOL: MEM_POOL  SEGMENT: ?XD?MTM808  6.*** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL  SYMBOL: SYSTEM_MODE  MODULE: .\debug\mtm808.obj (MTM808)  ADDRESS: 3A7CH  7.*** ERROR L118: REFERENCE MADE TO ERRONEOUS EXTERNAL  SYMBOL: ADPCM_STATE  MODULE: .\debug\SystemManager.obj (SYSTEMMANAGER)  ADDRESS: 358FH  references an unusable memory segment (may be caused by the previous over fllow error)  13.*** WARNING L1: UNRESOLVED EXTERNAL SYMBOL  SYMBOL: DATEI  MODULE: .\mtm809.LIB (CMDIF)  The entity of the external symbol cannot be found, so it cannot be linked