* static immap_t __iomem *imap or immap_t *imap;
@ 2007-03-06 11:08 DI BACCO ANTONIO - technolabs
2007-03-06 12:44 ` Arnd Bergmann
0 siblings, 1 reply; 2+ messages in thread
From: DI BACCO ANTONIO - technolabs @ 2007-03-06 11:08 UTC (permalink / raw)
To: linuxppc-embedded
Why should I use
static immap_t __iomem *imap;
And not
immap_t *imap;
in a driver?
when imap =3D ioremap_nocache()
In particular I know that __iomem is useful to the compiler to avoid
reordering and delaying io memory writes but what's the need for static
in this case?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: static immap_t __iomem *imap or immap_t *imap;
2007-03-06 11:08 static immap_t __iomem *imap or immap_t *imap; DI BACCO ANTONIO - technolabs
@ 2007-03-06 12:44 ` Arnd Bergmann
0 siblings, 0 replies; 2+ messages in thread
From: Arnd Bergmann @ 2007-03-06 12:44 UTC (permalink / raw)
To: linuxppc-embedded; +Cc: DI BACCO ANTONIO - technolabs
On Tuesday 06 March 2007, DI BACCO ANTONIO - technolabs wrote:
> Why should I use
> static immap_t =A0 __iomem *imap;
> And not
> immap_t *imap;
> in a driver?
> when imap =3D ioremap_nocache()
>=20
> In particular I know that __iomem is useful to the compiler to avoid
> reordering and delaying io memory writes but what's the need for static
> in this case?
The '__iomem' is use to allow static checking with the 'sparse' tool,
you really should use that before submitting any code. At this point,
gcc itself doesn't care. ioremap_nocache() returns __iomem, so anything
you assign it to should also be __iomem.
The 'static' is what you should use for _any_ symbol that is private
to your driver in order to avoid namespace pollution, it has nothing
to do whatsoever with whether it is about an __iomem address or not.
Arnd <><
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