[WinAVR-users] [ winavr-Bugs-2009732 ] Accessing EEPROM shows some anomalies

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Bugs item #2009732, was opened at 2008-07-03 07:30
Message generated for change (Comment added) made by arcanum
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Category: AVR-LibC
Group: None
>Status: Closed
>Resolution: Wont Fix
Priority: 5
Private: No
Submitted By: Willi (wiste)
Assigned to: Nobody/Anonymous (nobody)
Summary: Accessing EEPROM shows some anomalies

Initial Comment:
Using the latest WinAVR toolchain 20080610, the genereated binaries show anomalies when accessing odd addresses.

E.g.:
.
.
uint8_t byte1 EEMEM; /* even address */
uint8_t byte2 EEMEM; /* odd address */
uint8_t foo_var;
.
.
foo_var = eeprom_read_byte(&byte1); /* works fine */
.
.
foo_var = eeprom_read_byte(&byte2); /* fails by reseting the µC */
.
.

Similar functions that access the EEPROM show the same behavior.

The same code just works fine and doesn't show this behavior using WinAVR version 20060421.

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Comment By: Eric Weddington (arcanum)
Date: 2010-01-12 17:43

Message:
This needs to be reported to the avr-libc project at:
http://savannah.nongnu.org/bugs/?group=avr-libc

This is not a WinAVR bug. The WinAVR User Manual states that any potential
bugs in avr-libc (the standard C library for the AVR)
must be reported to the avr-libc project and not here.

Closed as "Won't Fix".

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Comment By: Nick Kolesnikov (nk2064)
Date: 2008-10-07 13:14

Message:
I'm have a similar problem :

#define EEPROM_SECTION  __attribute__ ((section (".eeprom")))
u16		eeprom_magic EEPROM_SECTION	 = 0x55AA;	

var uint16_t magic;
...
magic=eeprom_read_word(&eeprom_magic);
//freeze on first access :(

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Comment By: Willi (wiste)
Date: 2008-07-07 13:41

Message:
Logged In: YES 
user_id=2134926
Originator: YES

File Added: For Joerg.zip

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Comment By: Willi (wiste)
Date: 2008-07-03 09:30

Message:
Logged In: YES 
user_id=2134926
Originator: YES

I'm compiling for the mega 128.
-mmcu=atmega128

Further I attached the whole make file output.

-------- begin --------
avr-gcc (WinAVR 20080610) 4.3.0
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is
NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.

Size before:
AVR Memory Usage
----------------
Device: atmega128

Program:   10258 bytes (7.8% Full)
(.text + .data + .bootloader)

Data:        706 bytes (17.2% Full)
(.data + .bss + .noinit)

EEPROM:       71 bytes (1.7% Full)
(.eeprom)

Compiling C: RS1Tuele.c
avr-gcc -c -mmcu=atmega128 -I. -gdwarf-2 -DF_CPU=7372800UL -O0
-funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall
-Wstrict-prototypes -Wa,-adhlns=./RS1Tuele.lst  -std=gnu99 -Wundef -MMD -MP
-MF .dep/RS1Tuele.o.d RS1Tuele.c -o RS1Tuele.o 

Linking: RS1Tuele.elf
avr-gcc -mmcu=atmega128 -I. -gdwarf-2 -DF_CPU=7372800UL -O0
-funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall
-Wstrict-prototypes -Wa,-adhlns=RS1Tuele.o  -std=gnu99 -Wundef -MMD -MP -MF
.dep/RS1Tuele.elf.d RS1Tuele.o --output RS1Tuele.elf
-Wl,-Map=RS1Tuele.map,--cref   -Wl,-u,vfprintf -lprintf_flt  -lm

Creating load file for Flash: RS1Tuele.hex
avr-objcopy -O ihex -R .eeprom -R .fuse -R .lock RS1Tuele.elf
RS1Tuele.hex

Creating load file for EEPROM: RS1Tuele.eep
avr-objcopy -j .eeprom --set-section-flags=.eeprom="alloc,load" \
	--change-section-lma .eeprom=0 --no-change-warnings -O ihex RS1Tuele.elf
RS1Tuele.eep || exit 0

Creating Extended Listing: RS1Tuele.lss
avr-objdump -h -S -z RS1Tuele.elf > RS1Tuele.lss

Creating Symbol Table: RS1Tuele.sym
avr-nm -n RS1Tuele.elf > RS1Tuele.sym

Size after:
AVR Memory Usage
----------------
Device: atmega128

Program:   10258 bytes (7.8% Full)
(.text + .data + .bootloader)

Data:        706 bytes (17.2% Full)
(.data + .bss + .noinit)

EEPROM:       71 bytes (1.7% Full)
(.eeprom)

srec_cat RS1Tuele.hex -Intel -Output RS1Tuele.srec -Motorola -Line_Length
142
-------- end --------

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Comment By: Joerg Wunsch (joerg_wunsch)
Date: 2008-07-03 08:00

Message:
Logged In: YES 
user_id=1097648
Originator: NO

Please indicate which controller (-mmcu option) you are compiling for.

----------------------------------------------------------------------

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