Hi Bob, Avr-libc user manual, section on Memory Sections:
http://www.nongnu.org/avr-libc/user-manual/mem_sections.html According to that, it looks like .init2. A disassembly of the whole program should allow you to verify what happens in the .initX sections. I'm not sure why your program doesn't seem to work... Eric > -----Original Message----- > From: avr-gcc-list-bounces+eric.weddington=atmel....@nongnu.org [mailto:avr- > gcc-list-bounces+eric.weddington=atmel....@nongnu.org] On Behalf Of Bob > Paddock > Sent: Tuesday, July 03, 2012 11:06 AM > To: AVR-GCC > Subject: [avr-gcc-list] When does the Stack Frame Pointer (Y) get setup? > > When does the Stack Frame Pointer (Y) get setup? > > Should the following code work? I find it trashing memory in bss: > > void id_filter_init8( void ) __attribute__ ((naked)) __attribute__ > ((section(".init8"))); > void id_filter_init8( void ) > { > uint8_t ff_u8[128U]; > > /* memset() should really be used here */ > for( uint16_t idx_u16 = 0U; idx_u16 < (uint16_t) sizeof( ff_u8 ); idx_u16++ > ) > { > ff_u8[ idx_u16 ] = 0U; > } > > /* Anything that makes ff_u8 be used, so it is not optimized away in > this example: */ > eeprom_update_block ( ff_u8, sysgrp_mask_eeprom_u8, sizeof( > sysgrp_mask_eeprom_u8 ) ); > } > > .lss: > > 00008cc4 <__ctors_end>: > 8cc4: 11 24 eor r1, r1 > 8cc6: 1f be out 0x3f, r1 ; 63 > 8cc8: cf ef ldi r28, 0xFF ; 255 Set Y and stack > 8cca: df e3 ldi r29, 0x3F ; 63 > 8ccc: de bf out 0x3e, r29 ; 62 > 8cce: cd bf out 0x3d, r28 ; 61 > 8cd0: 00 e0 ldi r16, 0x00 ; 0 > 8cd2: 0c bf out 0x3c, r16 ; 60 > 8cd4: 18 be out 0x38, r1 ; 56 > 8cd6: 19 be out 0x39, r1 ; 57 > 8cd8: 1a be out 0x3a, r1 ; 58 > 8cda: 1b be out 0x3b, r1 ; 59 > > [snip lots of stuff that changes r28/r29, doesn't save them] > > [Is Y really a frame pointer value at this point?:] > > void id_filter_init8( void ) __attribute__ ((naked)) __attribute__ > ((section(".init8"))); > void id_filter_init8( void ) > { > 93b4: fe 01 movw r30, r28 > 93b6: 31 96 adiw r30, 0x01 ; 1 > #include "event.h" > extern void event_bug( void ); > #endif > > void id_filter_init8( void ) __attribute__ ((naked)) __attribute__ > ((section(".init8"))); > void id_filter_init8( void ) > 93b8: ce 01 movw r24, r28 > 93ba: 8f 57 subi r24, 0x7F ; 127 > 93bc: 9f 4f sbci r25, 0xFF ; 255 > { > uint8_t ff_u8[128U]; > > for( uint16_t idx_u16 = 0U; idx_u16 < (uint16_t) sizeof( ff_u8 ); idx_u16++ > ) > { > ff_u8[ idx_u16 ] = 0U; > 93be: 11 92 st Z+, r1 > void id_filter_init8( void ) __attribute__ ((naked)) __attribute__ > ((section(".init8"))); > void id_filter_init8( void ) > { > uint8_t ff_u8[128U]; > > for( uint16_t idx_u16 = 0U; idx_u16 < (uint16_t) sizeof( ff_u8 ); idx_u16++ > ) > 93c0: e8 17 cp r30, r24 > 93c2: f9 07 cpc r31, r25 > 93c4: e1 f7 brne .-8 ; 0x93be > <id_filter_init8+0xa> > { > ff_u8[ idx_u16 ] = 0U; > } > > [Looks like Y Frame Pointer is set and used as such from here on, and > gets saved in function calls:] > > MAIN_OS int main( void ) > { > 95d2: cd b7 in r28, 0x3d ; 61 > 95d4: de b7 in r29, 0x3e ; 62 > 95d6: cb 54 subi r28, 0x4B ; 75 > 95d8: d0 40 sbci r29, 0x00 ; 0 > 95da: cd bf out 0x3d, r28 ; 61 > 95dc: de bf out 0x3e, r29 ; 62 > > [more stuff] > > return( 0 ); /* When main() returns the .FINIsh function will be > called to put I/O in its lowest power state. Probably the same as the > power up state */ > }/* main() */ > 9aec: 80 e0 ldi r24, 0x00 ; 0 > 9aee: 90 e0 ldi r25, 0x00 ; 0 > 9af0: c5 5b subi r28, 0xB5 ; 181 > 9af2: df 4f sbci r29, 0xFF ; 255 > 9af4: cd bf out 0x3d, r28 ; 61 > 9af6: de bf out 0x3e, r29 ; 62 > 9af8: 08 95 ret > > Did I miss anything in the documentation that would tell me not to use > auto variables in .initX sections after .init2 that sets the stack? > > _______________________________________________ > AVR-GCC-list mailing list > AVR-GCC-list@nongnu.org > https://lists.nongnu.org/mailman/listinfo/avr-gcc-list _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org https://lists.nongnu.org/mailman/listinfo/avr-gcc-list
