Re: [PATCH 07/10] tools: Use -Og for debug builds when available

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.02.2021 16:39, Andrew Cooper wrote:
> The recommended optimisation level for debugging is -Og, and is what tools
> such as gdb prefer.  In practice, it equates to -01 with a few specific
> optimisations turned off.
> 
> abi-dumper in particular wants the libraries it inspects in this form.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

> --- a/tools/Rules.mk
> +++ b/tools/Rules.mk
> @@ -106,8 +106,9 @@ endif
>  CFLAGS_libxenlight += $(CFLAGS_libxenctrl)
>  
>  ifeq ($(debug),y)
> -# Disable optimizations
> -CFLAGS += -O0 -fno-omit-frame-pointer
> +# Use -Og if available, -O0 otherwise
> +dbg_opt_level := $(call cc-option,$(CC),-Og,-O0)
> +CFLAGS += $(dbg_opt_level) -fno-omit-frame-pointer

I wonder if we shouldn't do something similar for the hypervisor,
where we use -O1 for debug builds right now. At least when
DEBUG_INFO is also enabled, -Og may be better.

Jan