On Tue, Oct 5, 2021 at 10:59 PM <ckim@etri.re.kr> wrote:
In linux-5.4.21 code,
To prevent some variables from being ‘optimized out’ during kernel code analysis using gdb, I added in drivers/iommu/Makefile, ... ./include/linux/compiler-gcc.h:120:38: error: impossible constraint in 'asm'
120 | #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) ...
./arch/arm64/include/asm/jump_label.h:38:2: note: in expansion of macro 'asm_volatile_goto'
38 | asm_volatile_goto(
| ^~~~~~~~~~~~~~~~~
make[2]: *** [scripts/Makefile.build:266: drivers/iommu/io-pgtable-arm.o] Error 1
make[1]: *** [scripts/Makefile.build:509: drivers/iommu] Error 2
make: *** [Makefile:1652: drivers] Error 2
Does anybody know how can I use -O0 flag? (I tried -Og flag but some variables are still optimized out).
Does goto(x) eventually paste x? I.e., ##x? Also see token pasting at https://gcc.gnu.org/onlinedocs/cpp/Concatenation.html. Jeff