[build] Allow __asmcall to be used as a type attribute

The "used" attribute can be applied only to functions or variables,
which prevents the use of __asmcall as a type attribute.

Fix by removing "used" from the definition of __asmcall for i386 and
x86_64 architectures, and adding explicit __used annotations where
necessary.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

6 files changed, 9 insertions, 8 deletions

diff --git a/src/arch/i386/include/bits/compiler.h b/src/arch/i386/include/bits/compiler.h
index 7c4a09396..87201135f 100644
--- a/src/arch/i386/include/bits/compiler.h
+++ b/src/arch/i386/include/bits/compiler.h
@@ -9,7 +9,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #ifndef ASSEMBLY
 
 /** Declare a function with standard calling conventions */
-#define __asmcall __attribute__ (( used, cdecl, regparm(0) ))
+#define __asmcall __attribute__ (( cdecl, regparm(0) ))
 
 /**
  * Declare a function with libgcc implicit linkage
diff --git a/src/arch/x86/interface/pcbios/bios_console.c b/src/arch/x86/interface/pcbios/bios_console.c
index 52a02fba5..80ebf330e 100644
--- a/src/arch/x86/interface/pcbios/bios_console.c
+++ b/src/arch/x86/interface/pcbios/bios_console.c
@@ -443,7 +443,7 @@ struct console_driver bios_console __console_driver = {
  *
  * @v ix86		Registers as passed to INT 16
  */
-static __asmcall void bios_inject ( struct i386_all_regs *ix86 ) {
+static __asmcall __used void bios_inject ( struct i386_all_regs *ix86 ) {
 	unsigned int discard_a;
 	unsigned int scancode;
 	unsigned int i;
diff --git a/src/arch/x86/interface/pcbios/int13.c b/src/arch/x86/interface/pcbios/int13.c
index ca789a0d1..30530e197 100644
--- a/src/arch/x86/interface/pcbios/int13.c
+++ b/src/arch/x86/interface/pcbios/int13.c
@@ -1064,7 +1064,7 @@ static int int13_cdrom_read_boot_catalog ( struct san_device *sandev,
  * INT 13 handler
  *
  */
-static __asmcall void int13 ( struct i386_all_regs *ix86 ) {
+static __asmcall __used void int13 ( struct i386_all_regs *ix86 ) {
 	int command = ix86->regs.ah;
 	unsigned int bios_drive = ix86->regs.dl;
 	struct san_device *sandev;
diff --git a/src/arch/x86/interface/syslinux/comboot_call.c b/src/arch/x86/interface/syslinux/comboot_call.c
index e70f200e3..dc308dafe 100644
--- a/src/arch/x86/interface/syslinux/comboot_call.c
+++ b/src/arch/x86/interface/syslinux/comboot_call.c
@@ -220,7 +220,7 @@ static int comboot_fetch_kernel ( char *kernel_file, char *cmdline ) {
 /**
  * Terminate program interrupt handler
  */
-static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
+static __asmcall __used void int20 ( struct i386_all_regs *ix86 __unused ) {
 	rmlongjmp ( comboot_return, COMBOOT_EXIT );
 }
 
@@ -228,7 +228,7 @@ static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
 /**
  * DOS-compatible API
  */
-static __asmcall void int21 ( struct i386_all_regs *ix86 ) {
+static __asmcall __used void int21 ( struct i386_all_regs *ix86 ) {
 	ix86->flags |= CF;
 
 	switch ( ix86->regs.ah ) {
@@ -311,7 +311,7 @@ __weak int pxe_api_call_weak ( struct i386_all_regs *ix86 __unused ) {
 /**
  * SYSLINUX API
  */
-static __asmcall void int22 ( struct i386_all_regs *ix86 ) {
+static __asmcall __used void int22 ( struct i386_all_regs *ix86 ) {
 	ix86->flags |= CF;
 
 	switch ( ix86->regs.ax ) {
diff --git a/src/arch/x86/transitions/librm_test.c b/src/arch/x86/transitions/librm_test.c
index 77cf8022c..347d86a15 100644
--- a/src/arch/x86/transitions/librm_test.c
+++ b/src/arch/x86/transitions/librm_test.c
@@ -58,7 +58,8 @@ static struct profiler virt_call_profiler __profiler = { .name = "virt_call" };
 /**
  * Dummy function for profiling tests
  */
-static __asmcall void librm_test_call ( struct i386_all_regs *ix86 __unused ) {
+static __asmcall __used void
+librm_test_call ( struct i386_all_regs *ix86 __unused ) {
 	/* Do nothing */
 }
 
diff --git a/src/arch/x86_64/include/bits/compiler.h b/src/arch/x86_64/include/bits/compiler.h
index 46985da3e..5129f90d0 100644
--- a/src/arch/x86_64/include/bits/compiler.h
+++ b/src/arch/x86_64/include/bits/compiler.h
@@ -9,7 +9,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #ifndef ASSEMBLY
 
 /** Declare a function with standard calling conventions */
-#define __asmcall __attribute__ (( used, regparm(0) ))
+#define __asmcall __attribute__ (( regparm(0) ))
 
 /** Declare a function with libgcc implicit linkage */
 #define __libgcc