RE: [Xen-devel] Question about i386 ioremap()

["Puthiyaparambil, Aravindh" <aravindh.puthiyaparambil@xxxxxxxxxx>]

> Sounds OK to me; what part did you disagree with?

"The returned address is not guaranteed to be usable directly as a
virtual address." 

Why this should hold true for ioremap()? I see that this can be the case
for ioremap_nocache(). 

Furthermore if this comment is true, then please look at comments about
__ioremap() and __ioremap_nocache() in arch/xen/i386 or
x86_64/mm/ioremap.c. The comment I see for ioremap() is

/*
 * Remap an arbitrary physical address space into the kernel virtual
 * address space. Needed when the kernel wants to access high addresses
 * directly.

I am little confused here :-)

Aravindh

> -----Original Message-----
> From: Mark Williamson [mailto:mark.williamson@xxxxxxxxxxxx]
> Sent: Thursday, November 03, 2005 6:59 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Puthiyaparambil, Aravindh
> Subject: Re: [Xen-devel] Question about i386 ioremap()
> 
> > /**
> >  * ioremap     -   map bus memory into CPU space
> >  * @offset:    bus address of the memory
> >  * @size:      size of the resource to map
> >  *
> >  * ioremap performs a platform specific sequence of operations to
> >  * make bus memory CPU accessible via the readb/readw/readl/writeb/
> >  * writew/writel functions and the other mmio helpers. The returned
> >  * address is not guaranteed to be usable directly as a virtual
> >  * address.
> >  */
> >
> > Is this correct? Isn't this true only in the case of
ioremap_nocache()?

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