Re: [PATCH 1/7] xen/arm: Make make_cpus_node() compile at -Og

[Julien Grall <julien@xxxxxxx>]

Hi Andrew,

On 19/04/2021 15:01, Andrew Cooper wrote:
> When compiling at -Og:
>
>    domain_build.c: In function 'make_cpus_node':
>    domain_build.c:926:12: error: 'clock_valid' may be used uninitialized in 
> this function [-Werror=maybe-uninitialized]
>      926 |         if ( clock_valid )
>          |            ^
>
> The compiler hasn't spotted that clock_valid is always initialised after the
> "if ( !compatible )" check.  Initialise clock_valid to false.
Can you confirm which version this is affecting? We bumped the minimum 
version of GCC recently, so I want to make sure we don't add code to 
silence older compilers.
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien@xxxxxxx>
> CC: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> ---
>   xen/arch/arm/domain_build.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index b1d7b9849f..b10f5c8f85 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -831,7 +831,7 @@ static int __init make_cpus_node(const struct domain *d, 
> void *fdt)
>       /* Placeholder for cpu@ + a 32-bit hexadecimal number + \0 */
>       char buf[13];
>       u32 clock_frequency;
> -    bool clock_valid;
> +    bool clock_valid = false;
Would you mind to add something like:

/* Initialized silence at least GCC X.Y. */

With X.Y replaced with the version.

Cheers,

--
Julien Grall