diff options
Diffstat (limited to 'gcc/config/avr/avr-arch.h')
| -rw-r--r-- | gcc/config/avr/avr-arch.h | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/gcc/config/avr/avr-arch.h b/gcc/config/avr/avr-arch.h index 03b3263..d0a297d 100644 --- a/gcc/config/avr/avr-arch.h +++ b/gcc/config/avr/avr-arch.h @@ -166,7 +166,35 @@ AVR_ISA_RCALL assume these instructions are not available and we set the built-in macro __AVR_HAVE_JMP_CALL__ accordingly. This macro is used to determine a rough estimate of flash size in libgcc, and AVR-LibC uses - this macro to determine vector sizes. */ + this macro to determine vector sizes. + +AVR_ISA_FLMAP + The device has the NVMCTRL_CTRLB.FLMAP bitfield. The value of FLMAP + determines which 32 KiB segment of the program memory (flash) is visible + in the RAM address space at 0x8000. + + If Binutils support emulations avrxmega2_flmap resp. avrxmega4_flmap + (PR31124), then the location of the .rodata section can be determined + by means of option -m[no-]rodata-in-ram. If .rodata is located in flash, + the user can chose which 32 KiB flash block is visible in RAM space by + means of defining symbol __flmap. + + The startup code from AVR-LibC initializes FLMAP according to __flmap + provided one of the avrxmega*_flmap emulations is used. If avrxmega2/4 + is used, then the startup code does not initialize FLMAP. + + __AVR_HAVE_FLMAP__ is a macro defined in device-specs and supposed to be + consumed by code that sets FLMAP, like the startup code for example. + The macro is defined when all of the following conditions are met: + * The device is AVR_ISA_FLMAP. + * It's not known at compile time / assembler time whether or not .rodata + will be located in flash or in RAM. This implies Binutils PR31124. + * The definition of the macro is independent of -m[no-]rodata-in-ram. + + AVR_ISA_FLMAP does not affect multilib layout or selection in any way. + + For details on which symbols are defined in which way depending on the + emulation, see <Binutils>/ld/scripttempl/avr.sc. */ enum avr_device_specific_features { @@ -175,9 +203,12 @@ enum avr_device_specific_features AVR_SHORT_SP = 0x2, /* Stack Pointer has 8 bits width. */ AVR_ERRATA_SKIP = 0x4, /* device has a core erratum. */ AVR_ISA_LDS = 0x8, /* whether LDS / STS is valid for all data in static - storage. Only useful for reduced Tiny. */ - AVR_ISA_RCALL = 0x10 /* Use RJMP / RCALL even though JMP / CALL - are available (-mshort-calls). */ + storage. Only useful for reduced Tiny. */ + AVR_ISA_RCALL = 0x10, /* Use RJMP / RCALL even though JMP / CALL + are available (-mshort-calls). */ + AVR_ISA_FLMAP = 0x20 /* Has NVMCTRL_CTRLB.FLMAP to select which 32 KiB + block of program memory is visible in the RAM + address space. */ }; /* Map architecture to its texinfo string. */ |