On Wed, Oct 16, 2013 at 10:46:53PM +0300, Michael S. Tsirkin wrote:
> Old GCC didn't let you reference variable by
> number if it is listed with a specific register
> constraint, on the assumption you can just
> use the register name explicitly.
>
> Build fails with errors like this:
> a.c:6: error: invalid 'asm': invalid operand code 'd'
>
Is it worth to support such ancient compiler? Nobody complained till
now. BTW with your patch I still cannot compile with 4.2:
x86/s3.c: In function 'main':
x86/s3.c:145: error: inconsistent operand constraints in an 'asm'
> To fix, let's just use %eax %al etc.
>
Only %d0 does not work and dropping "d" fixes it since compiler can
figure out correct register from variable size. The patch bellow fixes
compilation for 4.2.
diff --git a/lib/x86/pci.c b/lib/x86/pci.c
index f95cd88..231668a 100644
--- a/lib/x86/pci.c
+++ b/lib/x86/pci.c
@@ -3,13 +3,13 @@
static void outl(unsigned short port, unsigned val)
{
- asm volatile("outl %d0, %w1" : : "a"(val), "Nd"(port));
+ asm volatile("outl %0, %w1" : : "a"(val), "Nd"(port));
}
static unsigned inl(unsigned short port)
{
unsigned data;
- asm volatile("inl %w1, %d0" : "=a"(data) : "Nd"(port));
+ asm volatile("inl %w1, %0" : "=a"(data) : "Nd"(port));
return data;
}
static uint32_t pci_config_read(pcidevaddr_t dev, uint8_t reg)
diff --git a/x86/s3.c b/x86/s3.c
index 71d3ff9..d568aa7 100644
--- a/x86/s3.c
+++ b/x86/s3.c
@@ -143,14 +143,14 @@ static inline int rtc_in(u8 reg)
{
u8 x = reg;
asm volatile("outb %b1, $0x70; inb $0x71, %b0"
- : "+a"(x) : "0"(x));
+ : "=a"(x) : "0"(x));
return x;
}
static inline void rtc_out(u8 reg, u8 val)
{
asm volatile("outb %b1, $0x70; mov %b2, %b1; outb %b1, $0x71"
- : "+a"(reg) : "0"(reg), "ri"(val));
+ : "=a"(reg) : "0"(reg), "ri"(val));
}
extern char resume_start, resume_end;
diff --git a/x86/vmexit.c b/x86/vmexit.c
index 3b945de..7e9af15 100644
--- a/x86/vmexit.c
+++ b/x86/vmexit.c
@@ -26,7 +26,7 @@ static void outw(unsigned short port, unsigned val)
static void outl(unsigned short port, unsigned val)
{
- asm volatile("outl %d0, %w1" : : "a"(val), "Nd"(port));
+ asm volatile("outl %0, %w1" : : "a"(val), "Nd"(port));
}
static unsigned int inb(unsigned short port)
--
Gleb.
--
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