[U-Boot] [PATCH] cfi_flash: Make all flash access functions weak

[Stefan Roese]

On Monday 17 November 2008, Haavard Skinnemoen wrote:
> Stefan Roese <sr at denx.de> wrote:
> > Old version without weak aliases:
> >    text    data     bss     dec     hex filename
> >  280964   20232   50788  351984   55ef0 ./u-boot
> >
> > New version with weak aliases:
> >    text    data     bss     dec     hex filename
> >  280520   20232   50788  351540   55d34 ./u-boot
> >
> > So the difference is 444 bytes (with gcc 4.2.2). I have to admit that
> > this is more than I thought. If necessary I could make this weak change
> > conditionally of course. I just didn't want to "pollute" to the source
> > with more #ifdef's.
>
> Looks like it's 444 bytes _smaller_ with weak functions...that's a bit
> surprising. From you comment, it sounds like it's really 444 bytes
> larger. Did you mix up the numbers?

Yes.

> If it's really 444 bytes larger, I think that's a bit much for
> something as simple as memory accessors. Ideally, they should boil down
> to a single instruction each.
>
> Perhaps you could allow overriding them in the board header by doing
> something like
>
> #ifndef flash_write8
> # #define flash_write8(value, addr)	__raw_writeb(value, addr)
> ...
>
> in cfi_flash.c?

I could do it this way, sure. But how about this version:

static void __flash_write8(u8 value, void *addr)
{
	__raw_writeb(value, addr);
}
...

#ifdef CONFIG_CFI_FLASH_USE_WEAK_ACCESSORS
void flash_write8(u8 value, void *addr)__attribute__((weak, alias("__flash_write8")));
...
#else
#define flash_read8	__flash_read8
...
#endif

We would still have the original accessor functions this way. And the
resulting source code looks a little "better" to me (less #ifdef's).

Best regards,
Stefan

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