Re: [PATCH v2 3/7] xen/common: Move Arm's bootfdt to common

[Jan Beulich <jbeulich@xxxxxxxx>]

On 15.12.2023 03:43, Shawn Anastasio wrote:
> Move Arm's bootfdt.c to xen/common so that it can be used by other
> device tree architectures like PPC and RISCV. Only a minor change to
> conditionalize a call to a function only available on EFI-supporting
> targets was made to the code itself.
> 
> Suggested-by: Julien Grall <julien@xxxxxxx>
> Signed-off-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
> ---
>  xen/arch/arm/Makefile                          |  1 -
>  xen/common/Makefile                            |  1 +
>  xen/common/device-tree/Makefile                |  1 +
>  xen/{arch/arm => common/device-tree}/bootfdt.c | 15 +++++++++------
>  4 files changed, 11 insertions(+), 7 deletions(-)
>  create mode 100644 xen/common/device-tree/Makefile
>  rename xen/{arch/arm => common/device-tree}/bootfdt.c (98%)

I think this wants to come with an update to ./MAINTAINERS, such that
the file doesn't change maintainership.

> --- a/xen/arch/arm/bootfdt.c
> +++ b/xen/common/device-tree/bootfdt.c
> @@ -431,12 +431,15 @@ static int __init early_scan_node(const void *fdt,
>  {
>      int rc = 0;
>  
> -    /*
> -     * If Xen has been booted via UEFI, the memory banks are
> -     * populated. So we should skip the parsing.
> -     */
> -    if ( !efi_enabled(EFI_BOOT) &&
> -         device_tree_node_matches(fdt, node, "memory") )
> +    if ( device_tree_node_matches(fdt, node, "memory") )
> +#if defined(CONFIG_ARM_EFI)
> +        /*
> +         * If Xen has been booted via UEFI, the memory banks are
> +         * populated. So we should skip the parsing.
> +         */
> +        if ( efi_enabled(EFI_BOOT) )
> +            return rc;
> +#endif

I'm not a DT maintainer, but I don't like this kind of #ifdef, the more
that maybe PPC and quite likely RISC-V are likely to also want to support
EFI boot. But of course there may be something inherently Arm-specific
here that I'm unaware of.

Jan