diff --git a/xen/arch/arm/include/asm/setup.h b/xen/arch/arm/include/asm/setup.h
index 0adfa4993a..2af7805125 100644
--- a/xen/arch/arm/include/asm/setup.h
+++ b/xen/arch/arm/include/asm/setup.h
@@ -25,8 +25,6 @@ struct map_range_data
     struct rangeset *irq_ranges;
 };
 
-extern domid_t max_init_domid;
-
 void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len);
 
 size_t estimate_efi_size(unsigned int mem_nr_banks);
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 6310a47d68..86532d0a35 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -62,8 +62,6 @@ struct cpuinfo_arm __read_mostly system_cpuinfo;
 bool __read_mostly acpi_disabled;
 #endif
 
-domid_t __read_mostly max_init_domid;
-
 static __used void noreturn init_done(void)
 {
     /* Must be done past setting system_state. */
diff --git a/xen/arch/ppc/include/asm/setup.h b/xen/arch/ppc/include/asm/setup.h
index e4f64879b6..956fa6985a 100644
--- a/xen/arch/ppc/include/asm/setup.h
+++ b/xen/arch/ppc/include/asm/setup.h
@@ -1,6 +1,4 @@
 #ifndef __ASM_PPC_SETUP_H__
 #define __ASM_PPC_SETUP_H__
 
-#define max_init_domid (0)
-
 #endif /* __ASM_PPC_SETUP_H__ */
diff --git a/xen/arch/riscv/include/asm/setup.h b/xen/arch/riscv/include/asm/setup.h
index 2215894cfb..73ce2f2933 100644
--- a/xen/arch/riscv/include/asm/setup.h
+++ b/xen/arch/riscv/include/asm/setup.h
@@ -5,8 +5,6 @@
 
 #include <xen/types.h>
 
-#define max_init_domid (0)
-
 void setup_mm(void);
 
 void copy_from_paddr(void *dst, paddr_t paddr, unsigned long len);
diff --git a/xen/arch/x86/include/asm/setup.h b/xen/arch/x86/include/asm/setup.h
index b01e83a8ed..5925c5f39c 100644
--- a/xen/arch/x86/include/asm/setup.h
+++ b/xen/arch/x86/include/asm/setup.h
@@ -68,6 +68,4 @@ extern bool opt_dom0_verbose;
 extern bool opt_dom0_cpuid_faulting;
 extern bool opt_dom0_msr_relaxed;
 
-#define max_init_domid (0)
-
 #endif
diff --git a/xen/common/domid.c b/xen/common/domid.c
index b0258e477c..c0cb025609 100644
--- a/xen/common/domid.c
+++ b/xen/common/domid.c
@@ -8,8 +8,13 @@
  * Copyright 2025 Ford Motor Company
  */
 
+#include <xen/dom0less-build.h>
 #include <xen/domain.h>
 
+#ifdef CONFIG_DOM0LESS_BOOT
+domid_t __ro_after_init max_init_domid;
+#endif
+
 static DEFINE_SPINLOCK(domid_lock);
 static DECLARE_BITMAP(domid_bitmap, DOMID_FIRST_RESERVED);
 
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index fcacf37c52..e4df0bbc2e 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -30,7 +30,7 @@
 #include <xen/early_printk.h>
 #include <xen/warning.h>
 #include <xen/pv_console.h>
-#include <asm/setup.h>
+#include <xen/dom0less-build.h>
 #include <xen/sections.h>
 #include <xen/consoled.h>
 
diff --git a/xen/include/xen/dom0less-build.h b/xen/include/xen/dom0less-build.h
index 4118dec76c..75bfaa185f 100644
--- a/xen/include/xen/dom0less-build.h
+++ b/xen/include/xen/dom0less-build.h
@@ -4,6 +4,9 @@
 #define XEN_DOM0LESS_BUILD_H
 
 #include <xen/stdbool.h>
+#include <xen/types.h>
+
+#include <public/xen.h>
 
 struct domain;
 
@@ -13,6 +16,9 @@ struct boot_domain;
 struct dt_device_node;
 struct kernel_info;
 
+/* Highest domain ID assigned to a boot-time (dom0less) domain. */
+extern domid_t max_init_domid;
+
 /*
  * List of possible features for dom0less domUs
  *
@@ -72,6 +78,8 @@ static inline bool is_dom0less_mode(void)
 }
 static inline void set_xs_domain(struct domain *d) {}
 
+#define max_init_domid 0
+
 #endif /* CONFIG_DOM0LESS_BOOT */
 
 #endif /* __ASM_GENERIC_DOM0LESS_BUILD_H__ */