This code will link against parts of the startup code
from AVR-LibC when it is needed to init bit-field FLMAP.
Johann
--
AVR: target/112944 - Addendum: Link code to initialize NVMCTRL_CTRLB.FLMAP
For devices that see a part for the flash memory in the RAM address space,
bit-field NVMCTRL_CTRLB.FLMAP must match the value of symbol __flmap.
This is achieved by dragging in startup code from lib<mcu>.a.
The mechanism is the same like for libgcc's __do_copy_data and
__do_clear_bss.
The code is implemented in AVR-LibC #931 and can be dragged by referencing
__do_flmap_init.
In addition to setting FLMAP, that code also sets bit FLMAPLOCK provided
symbol __flmap_lock has a non-zero value. This protects FLMAP from future
changes.
When the __do_flmap_init code is not wanted, the symbol can be satisfied by
linking with -Wl,--defsym,__do_flmap_init=0
gcc/
PR target/112944
* config/avr/gen-avr-mmcu-specs.cc (print_mcu) [have_flmap]:
<*link_rodata_in_ram>: Spec undefs symbol __do_flmap_init
when not linked with -mrodata-in-ram.
diff --git a/gcc/config/avr/gen-avr-mmcu-specs.cc
b/gcc/config/avr/gen-avr-mmcu-specs.cc
index ea69145d404..bb94bea12b0 100644
--- a/gcc/config/avr/gen-avr-mmcu-specs.cc
+++ b/gcc/config/avr/gen-avr-mmcu-specs.cc
@@ -369,7 +369,10 @@ print_mcu (const avr_mcu_t *mcu, const McuInfo &mi)
}
// -m[no-]rodata-in-ram affects linking. Sanity check its usage.
- fprintf (f, "*link_rodata_in_ram:\n\t%%(check_rodata_in_ram)\n\n");
+ fprintf (f, "*link_rodata_in_ram:\n\t%%(check_rodata_in_ram)");
+ if (mi.is_device && mi.have_flmap)
+ fprintf (f, " %%{!mrodata-in-ram:-u __do_flmap_init}");
+ fprintf (f, "\n\n");
// Specs known to GCC.
