Re: Little help with Seabios PV-Drivers for XEN

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Mar 09, 2012 at 08:35:40AM +0900, Daniel Castro wrote:
> Hello All,
> 
> I have a little setback with the development of PV Drivers for Xen in SeaBIOS.

Hey, seems I read your emails out of sync.

> The initialization code that runs in 32 Bit is working properly.
> But, when the system tries to read on the disk I use the ring macros
> to get a request. The macro usage looks like this:
> struct blkif_ring * shared = memalign_low(4096,4096); //return
> 0x000fd630 this above 16bit address space
> SHARED_RING_INIT(shared);
> So far I have a pointer located at 0x0009a000
> Under 32bit the struct is correct and all is working according to plan.
> 
> But on 16bit operation read on disk I have
> struct blkfront_info * shared_ring =
> container_of(op->drive_g.info->shared)); // I get d630 I should get it
> from the correct segment, but how?
> RING_GET_REQUEST(shared_ring); //this returns 0xffff and should be
> something 0xa010 segment SS or something like that
> 
> SeaBios has some macros that convert a pointer in 32Bit to 16Bit by
> changing the segment register, yet I do not know in what segment the
> ring is located, and the macros are not applied inside the procedure
> of the macro, for example:

There should be some way to set your physical address (so
9a000) to a segment?

> MAKE_FLATPTR(GET_SEG(SS),RING_GET_REQUEST(shared_ring));
> But this will change a 16Bit pointer of segment SS to a 32 bit
> segment. There is also the reverse but, again I do not know the
> segment in which I should look for. Lastly the process inside the
> macro does not get this benefin, and I do not know if the macro will
> work with a pointer of size 16bits.

16-bits should be fine. The problem is if you run your pointer
outside the 16-bit segment.

> 
> Any help will be GREATLY appreciated, I am almost done.
> 
> Thanks,
> 
> Daniel
> -- 
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> | |   | Daniel Castro,                |
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