[U-Boot-Users] Help with "warning: 'alias' attribute ignored"

[U-Boot-Users] Help with "warning: 'alias' attribute ignored"

[Timur Tabi]

I'm trying to write code that uses the "pragma weak" feature of gcc to define a
global variable that is used only if it isn't defined somewhere else.  I thought
I had it working, but then I noticed this:

powerpc-linux-gnu-gcc -g  -Os   -fPIC -ffixed-r14 -meabi -D__KERNEL__
-DTEXT_BASE=0xFE000000 -I/temp/u-boot.281/include -fno-builtin -ffreestanding
-nostdinc -isystem
/opt/freescale/usr/local/gcc-4.2.72-eglibc-2.5.72-1/powerpc-linux-gnu/lib/gcc/powerpc-linux-gnu/4.2.1/include
-pipe  -DCONFIG_PPC -D__powerpc__ -DCONFIG_MPC83XX -DCONFIG_E300 -ffixed-r2
-msoft-float -Wall -Wstrict-prototypes -c -o fsl_i2c.o fsl_i2c.c
fsl_i2c.c: In function 'get_fdr':
fsl_i2c.c:72: warning: 'alias' attribute ignored


Here's the code in question, which is in fsl_i2c.c:

#pragma weak fsl_i2c_speed_map = default_fsl_i2c_speed_map

struct fsl_i2c_speed_map default_fsl_i2c_speed_map[] = {
	{0, 0x3F}, {-1, 0x3F}
};

static u8 get_fdr(unsigned int i2c_clk, unsigned int speed)
{
	extern struct fsl_i2c_speed_map fsl_i2c_speed_map[];
	...


Line 72 is the "extern struct fsl..." line.

In a platform-specific file, I have this:

struct fsl_i2c_speed_map fsl_i2c_speed_map[] = {
	{0, 0x20},
	...

What I'm trying to do is to make it so that you don't need to define the
fsl_i2c_speed_map[] array in your platform file.  However, I get the warning
message if fsl_i2c_speed_map[] *is* defined in the platform file.

Am I just doing this wrong, or is there a way to avoid the compiler warning?

-- 
Timur Tabi
Linux kernel developer at Freescale

[U-Boot-Users] Help with "warning: 'alias' attribute ignored"

[Jean-Christophe PLAGNIOL-VILLARD]

On 16:54 Tue 11 Mar     , Timur Tabi wrote:
> I'm trying to write code that uses the "pragma weak" feature of gcc to define a
> global variable that is used only if it isn't defined somewhere else.  I thought
> I had it working, but then I noticed this:
> 
> powerpc-linux-gnu-gcc -g  -Os   -fPIC -ffixed-r14 -meabi -D__KERNEL__
> -DTEXT_BASE=0xFE000000 -I/temp/u-boot.281/include -fno-builtin -ffreestanding
> -nostdinc -isystem
> /opt/freescale/usr/local/gcc-4.2.72-eglibc-2.5.72-1/powerpc-linux-gnu/lib/gcc/powerpc-linux-gnu/4.2.1/include
> -pipe  -DCONFIG_PPC -D__powerpc__ -DCONFIG_MPC83XX -DCONFIG_E300 -ffixed-r2
> -msoft-float -Wall -Wstrict-prototypes -c -o fsl_i2c.o fsl_i2c.c
> fsl_i2c.c: In function 'get_fdr':
> fsl_i2c.c:72: warning: 'alias' attribute ignored
> 
> 
> Here's the code in question, which is in fsl_i2c.c:
> 
replace this
> #pragma weak fsl_i2c_speed_map = default_fsl_i2c_speed_map
> 
> struct fsl_i2c_speed_map default_fsl_i2c_speed_map[] = {
> 	{0, 0x3F}, {-1, 0x3F}
> };

by this

struct fsl_i2c_speed_map fsl_i2c_speed_map[] __attribute__((weak))= {
	{0, 0x3F}, {-1, 0x3F}
};

> static u8 get_fdr(unsigned int i2c_clk, unsigned int speed)
> {
and remove this line
> 	extern struct fsl_i2c_speed_map fsl_i2c_speed_map[];

Best Regards,
J.