Re: [XenPPC] [PATCH 1/3] libxc: add start_info_t node to devtree

[Ryan Harper <ryanh@xxxxxxxxxx>]

* Jimi Xenidis <jimix@xxxxxxxxxxxxxx> [2007-01-25 14:40]:
> >>Since you later look for the console_mfn and store_mfn later, it
> >>would be better in the caller and pass then in.
> >>FYI: It is xend that decides where store and console go. shared_info
> >>is a hypervisor contract so you can continue to calculate it here if
> >>you want.
> >>
> >>Also the devtree should not contain MFNs for frame numbers of any
> >>kind, simply addresses.
> >
> >I don't follow.  the start_info_t structure explicitly wants an  
> >mfn, how
> >else am I suppose to fill that value out in linux?
> 
> they are MFNs on x86, in PPC they are domain physical addresses.

Maybe I've just got it named funny, I don't know.  And I'm still
confused as to what you want me to put in?  

The value that I put in start_info->console.domU.mfn is:

((rma_pages << 12) - (2*PAGE_SIZE)) >> PAGE_SHIFT

where rma_pages = (1 << 26) >> PAGE_SHIFT

the resulting value is 0x3ffe.  Is this value correct and I just have an
incorrect name for it (mfn)?  Am I getting lucky? I've tested the
patches and dom0 and domU boot.

> 
> >
> >>
> >>>{
> >>>    struct boot_param_header *bph = NULL;
> >>>    uint64_t val[2];
> >>>    uint32_t val32[2];
> >>>    unsigned long remaining;
> >>>-    unsigned long rma_reserve = 4 * PAGE_SIZE;
> >>>+    unsigned long rma_reserve = 3 * PAGE_SIZE;
> >>
> >>base this on MIN(store, console)
> >
> >Why? Don't we always have a store and a console page?
> 
> yes we do, but they could be in any order, all you are trying to do  
> is make sure the pages are in the reserve map.  Another possibility  
> is you could not assume contiguity and create a reservation entry for  
> each of the three pages.

I don't understand what is wrong with the above.  We are reserving the
last X pages of the RMA.  1 for shared_info, 1 for console, one for
store.  I futher don't understand what the value MIN(store,console)
gives me.  Sorry for being dense here.


-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@xxxxxxxxxx

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