[U-Boot] Turning optimizations off
Hello,
I am debugging u-boot with a BDI and am running into a case where a variable gets optimized out. For the sake of debugging I am trying to turn off optimizations. I have the following in u-boot-2009.01/config.mk, but GDB still reports optimizations:
OPTFLAGS= -Os -fno-schedule-insns -fno-schedule-insns2 #-fomit-frame-pointer
(gdb) stepi
0x0ff78750 in get_table_entry_name (table=<value optimized out>,
msg=0xff9e1a8 "Unknown Architecture", id=7) at image.c:544
544 }
Does anyone know how to completely turn optimization off? Using no -O flag results in u-boot not compiling.
Fahd Abidi Product Manager - Technical Tools and Development Ultimate Solutions, Inc. ================================================================ Your Single Source for Professional Development Tools and Embedded Solutions Ph: 978-455-3383 x255 Fx: 978-926-3091 Email: fabidi@ultsol.com Visit: http://www.ultsol.com http://www.ultsol.com/
Dear "Fahd Abidi",
In message 71DEA556544D7A4F9C6848402D8184340C45D7@usi01.ultsol.local you wrote:
I have the following in u-boot-2009.01/config.mk, but GDB still reports optimizations:
OPTFLAGS= -Os -fno-schedule-insns -fno-schedule-insns2 #-fomit-frame-pointer
Well, "-Os" means "optimize for minimal code size"...
(gdb) stepi
0x0ff78750 in get_table_entry_name (table=<value optimized out>,
... so it is only natural that GCC will eliminate unneeded code.
Does anyone know how to completely turn optimization off? Using no -O flag results in u-boot not compiling.
You cannot globally disable optimization. You might get away with doing this on a per-file level, but there is no guarantee for that.
It is better to arrange to keep optimization turned on - after all, this is the real code that will later be running.
Best regards,
Wolfgang Denk
Fahd Abidi wrote:
Hello,
I am debugging u-boot with a BDI and am running into a case where a variable gets optimized out. For the sake of debugging I am trying to turn off optimizations. I have the following in u-boot-2009.01/config.mk, but GDB still reports optimizations:
OPTFLAGS= -Os -fno-schedule-insns -fno-schedule-insns2 #-fomit-frame-pointer
(gdb) stepi
0x0ff78750 in get_table_entry_name (table=<value optimized out>,
If you (temporarily) put "volatile" on the variable, the compiler should not optimize it out. Obviously, this is a limited solution, but may get your past your problem.
[snip]
Does anyone know how to completely turn optimization off? Using no -O flag results in u-boot not compiling.
Theoretically, you could compile individual files w/o optimization (e.g. if you compile it by hand, make shouldn't re-compile it). I doubt that you want to go there, though...
Fahd Abidi
Good luck, gvb
participants (3)
-
Fahd Abidi -
Jerry Van Baren -
Wolfgang Denk