Re: [PATCH] Arm64: fix build with gcc 10

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

I would suggest: "xen/arm64: Force GCC to always inline generic atomics 
helpers".
On 08/09/2020 13:53, Jan Beulich wrote:
> With gcc10 inlining is (no longer?) the default for certain atomics.
How about the following:

"Recent versions of GCC (at least GCC10) will not inline generic atomics 
helpers. Instead it will expect the software to either link with 
libatomic.so or implement the helpers.
To keep the previous behavior, force GCC to always inline the generic 
atomics helpers.
Long term we probably want to avoid relying on GCC atomics helpers as 
this doesn't allow us to switch between LSE and LL/SC atomic.
"

> Suggested-by: Julien Grall <jgrall@xxxxxxxxxx>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>
> --- a/xen/arch/arm/arch.mk
> +++ b/xen/arch/arm/arch.mk
> @@ -12,6 +12,7 @@ CFLAGS-$(CONFIG_ARM_32) += -mcpu=cortex-
>   
>   CFLAGS-$(CONFIG_ARM_64) += -mcpu=generic
>   CFLAGS-$(CONFIG_ARM_64) += -mgeneral-regs-only # No fp registers etc
> +$(call cc-option-add,CFLAGS-$(CONFIG_ARM_64),CC,-mno-outline-atomics)
>   
>   ifneq ($(filter command line environment,$(origin CONFIG_EARLY_PRINTK)),)
>       $(error You must use 'make menuconfig' to enable/disable early printk now)
--
Julien Grall