Hello,
I try to build a 64-bit RISC-V tool chain for RTEMS. RTEMS doesn't use
virtual memory. The reference chips for 64-bit RISC-V such as FU540-C000
locate the RAM at 0x8000_0000. This forces me to use -mcmodel=medany in
64-bit mode. The ctrbegin.o contains this code (via crtstuff.c):
extern void *__deregister_frame_info (const void *)
__attribute__ ((weak));
...
# 370 "libgcc/crtstuff.c"
static void __attribute__((used))
__do_global_dtors_aux (void)
{
static _Bool completed;
if (__builtin_expect (completed, 0))
return;
# 413 "libgcc/crtstuff.c"
deregister_tm_clones ();
# 423 "libgcc/crtstuff.c"
if (__deregister_frame_info)
__deregister_frame_info (__EH_FRAME_BEGIN__);
completed = 1;
}
Which is:
.text
.align 1
.type __do_global_dtors_aux, @function
__do_global_dtors_aux:
lbu a5,completed.3298
bnez a5,.L22
addi sp,sp,-16
sd ra,8(sp)
call deregister_tm_clones
lla a5,__deregister_frame_info
beqz a5,.L17
lla a0,__EH_FRAME_BEGIN__
call __deregister_frame_info
.L17:
ld ra,8(sp)
li a5,1
sb a5,completed.3298,a4
addi sp,sp,16
jr ra
.L22:
ret
If I link an executable I get this:
/opt/rtems/5/lib64/gcc/riscv64-rtems5/9.0.0/../../../../riscv64-rtems5/bin/ld:
/opt/rtems/5/lib64/gcc/riscv64-rtems5/9.0.0/crtbegin.o: in function `.L0 ':
crtstuff.c:(.text+0x72): relocation truncated to fit: R_RISCV_CALL
against undefined symbol `__deregister_frame_info'
I guess, that the resolution of the weak reference to the undefined
symbol __deregister_frame_info somehow sets __deregister_frame_info to
the absolute address 0 which is illegal in the following "call
__deregister_frame_info"? Is this construct with weak references and a
-mcmodel=medany supported on RISC-V at all?
If I change crtstuff.c like this using weak function definitions
diff --git a/libgcc/crtstuff.c b/libgcc/crtstuff.c
index 5e894455e16..770e3420c92 100644
--- a/libgcc/crtstuff.c
+++ b/libgcc/crtstuff.c
@@ -177,13 +177,24 @@ call_ ## FUNC
(void) \
/* References to __register_frame_info and __deregister_frame_info should
be weak in this file if at all possible. */
-extern void __register_frame_info (const void *, struct object *)
- TARGET_ATTRIBUTE_WEAK;
+extern void __register_frame_info (const void *, struct object *) ;
+TARGET_ATTRIBUTE_WEAK void __register_frame_info (const void *unused,
struct object *unused2)
+{
+ (void)unused;
+ (void)unused2;
+}
+
extern void __register_frame_info_bases (const void *, struct object *,
void *, void *)
TARGET_ATTRIBUTE_WEAK;
-extern void *__deregister_frame_info (const void *)
- TARGET_ATTRIBUTE_WEAK;
+
+extern void *__deregister_frame_info (const void *);
+TARGET_ATTRIBUTE_WEAK void *__deregister_frame_info (const void *unused)
+{
+ (void)unused;
+ return 0;
+}
+
extern void *__deregister_frame_info_bases (const void *)
TARGET_ATTRIBUTE_WEAK;
extern void __do_global_ctors_1 (void);
then the example program links.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
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