Re: [RFC v1 4/8] x86/init: add linker table support

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> +static bool x86_init_fn_supports_subarch(struct x86_init_fn *fn)
> +{
> +	if (!fn->supp_hardware_subarch) {
> +		pr_err("Init sequence fails to declares any supported subarchs: %pF\n", fn->early_init);
> +		WARN_ON(1);
> +	}
> +	if (BIT(boot_params.hdr.hardware_subarch) & fn->supp_hardware_subarch)
> +		return true;
> +	return false;
> +}

So the logic for this working is that boot_params.hdr.hardware_subarch

And the macros define two: BIT(X86_SUBARCH_PC) or BIT(X86_SUBARCH_XEN).

But hardware_subarch by default is set to zero. Which means if GRUB2, PXELinux, Xen multiboot1
don't set it - then the X86_SUBARCH_PC is choosen right?

 1 << 0 & 1 << X86_SUBARCH_PC (which is zero).

For this to nicely work with Xen it ought to do this:

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 993b7a7..6cf9afd 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1676,6 +1676,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
        boot_params.hdr.ramdisk_image = initrd_start;
        boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
        boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
+       boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN;
 
        if (!xen_initial_domain()) {
                add_preferred_console("xenboot", 0, NULL);


?