Re: [Qemu-devel] RFC: guest-side retrieval of fw_cfg file

[Gabriel L. Somlo]

On Thu, Jul 16, 2015 at 01:27:15PM -0600, Eric Blake wrote:
> On 07/15/2015 06:43 PM, Gabriel L. Somlo wrote:
> 
> > 
> > OK, so I replaced my port i/o with mmio equivalents:
> > 
> > -#define FW_CFG_PORT_CTL  0x510
> > +#define FW_CFG_PORT_CTL  (void *)0x09020008
> > 
> > -#define FW_CFG_PORT_DATA 0x511
> > +#define FW_CFG_PORT_DATA (void *)0x09020000
> 
> Under-parenthesized; you'll want:
> 
> #define FW_CFG_PORT_DATA ((void *)0x09020000)
> 
> to be useful in all possible locations where an identifier can appear in
> an expression.
> 
> > 
> > -       outw(select, FW_CFG_PORT_CTL);
> > +       writew(select, FW_CFG_PORT_CTL);
> > 
> > -       inb(FW_CFG_PORT_DATA);
> > +       readb(FW_CFG_PORT_DATA);
> > 
> > -       insb(FW_CFG_PORT_DATA, buf, count);
> > +       readsb(FW_CFG_PORT_DATA, buf, count);
> 
> But as it doesn't affect your usage here...
> 
> > 
> > I'm probably missing something that'll turn out to be really obvious
> > in retrospect... :)
> 
> I probably didn't spot the really obvious problem.

After some meditation (and digging around), I now think I may have missed
some of the pomp and circumstance surrounding mmio access, beyond the simple
writew/readsb calls I was using. Such as [request|check|release]_mem_region(),
ioremap(), and maybe even ioport_[map|unmap](), to hopefully make things
more uniform across the mmio vs. ioport architectures :)

Guess Section 9.4 of LDD3 is my new bestest friend :)
(http://www.makelinux.net/ldd3/chp-9-sect-4)

Thanks,
--Gabriel