a driver can depend on xcall and get this glue code compiled so it will
work on arm64.

ok?

Index: arm64/cpu.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/arm64/cpu.c,v
diff -u -p -r1.142 cpu.c
--- arm64/cpu.c	1 Jul 2025 11:10:36 -0000	1.142
+++ arm64/cpu.c	13 Jul 2025 06:01:15 -0000
@@ -1595,6 +1595,10 @@ cpu_attach(struct device *parent, struct
 		}
 #ifdef MULTIPROCESSOR
 	}
+
+#if NXCALL > 0
+	cpu_xcall_establish(ci);
+#endif
 #endif
 
 #if NKSTAT > 0
Index: dev/agintc.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/dev/agintc.c,v
diff -u -p -r1.63 agintc.c
--- dev/agintc.c	6 Jul 2025 12:22:31 -0000	1.63
+++ dev/agintc.c	13 Jul 2025 06:01:15 -0000
@@ -1428,6 +1428,10 @@ agintc_ipi_handler(void *v)
 			agintc_ipi_ddb(v);
 		if (ISSET(reasons, 1 << ARM_IPI_HALT))
 			agintc_ipi_halt(v);
+#if NXCALL > 0
+		if (ISSET(reasons, 1 << ARM_IPI_XCALL))
+			cpu_xcall_dispatch(ci);
+#endif
 	}
 
 	return (1);
Index: dev/ampintc.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/dev/ampintc.c,v
diff -u -p -r1.33 ampintc.c
--- dev/ampintc.c	6 Jul 2025 12:22:31 -0000	1.33
+++ dev/ampintc.c	13 Jul 2025 06:01:15 -0000
@@ -1033,6 +1033,10 @@ ampintc_ipi_handler(void *v)
 			ampintc_ipi_ddb(v);
 		if (ISSET(reasons, 1 << ARM_IPI_HALT))
 			ampintc_ipi_halt(v);
+#if NXCALL > 0
+		if (ISSET(reasons, 1 << ARM_IPI_XCALL))
+			cpu_xcall_dispatch(ci);
+#endif
 	}
 
 	return (1);
Index: dev/aplintc.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/dev/aplintc.c,v
diff -u -p -r1.19 aplintc.c
--- dev/aplintc.c	6 Jul 2025 12:22:31 -0000	1.19
+++ dev/aplintc.c	13 Jul 2025 06:01:15 -0000
@@ -689,6 +689,10 @@ aplintc_handle_ipi(struct aplintc_softc 
 #endif
 		if (ISSET(reasons, 1 << ARM_IPI_HALT))
 			cpu_halt();
+#if NXCALL > 0
+		if (ISSET(reasons, 1 << ARM_IPI_XCALL))
+			cpu_xcall_dispatch(ci);
+#endif
 	}
 
 	sc->sc_ipi_count.ec_count++;
Index: dev/bcm2836_intr.c
===================================================================
RCS file: /cvs/src/sys/arch/arm64/dev/bcm2836_intr.c,v
diff -u -p -r1.16 bcm2836_intr.c
--- dev/bcm2836_intr.c	6 Jul 2025 12:22:31 -0000	1.16
+++ dev/bcm2836_intr.c	13 Jul 2025 06:01:15 -0000
@@ -638,6 +638,10 @@ bcm_intc_handle_ipi(void)
 		db_enter();
 	}
 #endif
+#if NXCALL > 0
+	if (ISSET(mbox_val, 1 << ARM_IPI_XCALL))
+		cpu_xcall_dispatch(curcpu());
+#endif
 }
 
 void
Index: include/cpu.h
===================================================================
RCS file: /cvs/src/sys/arch/arm64/include/cpu.h,v
diff -u -p -r1.51 cpu.h
--- include/cpu.h	11 Feb 2025 22:27:09 -0000	1.51
+++ include/cpu.h	13 Jul 2025 06:01:15 -0000
@@ -57,6 +57,8 @@
 
 #ifdef _KERNEL
 
+#include "xcall.h"
+
 /*
  * Kernel-only definitions
  */
@@ -112,6 +114,9 @@ void cpu_identify_cleanup(void);
 #include <sys/sched.h>
 #include <sys/srp.h>
 #include <uvm/uvm_percpu.h>
+#if NXCALL > 0
+#include <sys/xcall.h>
+#endif
 
 struct cpu_info {
 	struct device		*ci_dev; /* Device corresponding to this CPU */
@@ -167,6 +172,9 @@ struct cpu_info {
 
 #ifdef MULTIPROCESSOR
 	struct srp_hazard	ci_srp_hazards[SRP_HAZARD_NUM];
+#if NXCALL > 0
+	struct xcall_cpu	ci_xcall;
+#endif
 #define __HAVE_UVM_PERCPU
 	struct uvm_pmr_cache	ci_uvm;
 	volatile int		ci_flags;
Index: include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/arm64/include/intr.h,v
diff -u -p -r1.25 intr.h
--- include/intr.h	30 Jun 2025 14:19:20 -0000	1.25
+++ include/intr.h	13 Jul 2025 06:01:15 -0000
@@ -199,6 +199,9 @@ extern void (*intr_send_ipi_func)(struct
 #define ARM_IPI_NOP	0
 #define ARM_IPI_DDB	1
 #define ARM_IPI_HALT	2
+#define ARM_IPI_XCALL	3
+
+#define cpu_xcall_ipi(_ci) arm_send_ipi((_ci), ARM_IPI_XCALL)
 
 #ifdef DIAGNOSTIC
 /*