Re: [Qemu-devel] PowerPC64 and more

[J. Mayer]

On Fri, 2005-07-22 at 00:58 +0200, Filip Navara wrote:
> J. Mayer wrote:
> 
> >On Fri, 2005-07-22 at 00:10 +0200, Filip Navara wrote:
> >  
> >
> >>J. Mayer wrote:

[...]
> >>wow, you repeated my and Fabrice's mistake once more ... think about the 
> >>code below more :)
> >>note: when you'll be done thinking or run out of ideas see my x86-64 
> >>patches that i sent to ML this morning.
> >
> >Without this patch, it crashes at the first instruction trying to access
> >the BIOS.
> >And your patch does not solve the problem:
> >on a real PowerPC 64 machine, we can use the whole 64 bits virtual
> >space.
> >We agreed with Fabrice that there should be at least one more
> >indirection in page mapping, because it would cost too much memory to
> >try to map the whole needed memory space in one table, even if we can
> >"forget" some of the middle bits in most cases.
> >  
> >
> Ok, so far so good and I agree with that (I even had the third level of 
> indirection implemented)...
> 
> >Then, you're right, this patch is ugly but allows not to crash until we
> >have a correct solution with indirect tables to get a very large virtual
> >space.
> >
> >  
> >
> ... but read it once more. You're cutting up the "index", not "index >> 
> L2_BITS".

In fact, I did not want to be too invasive outside of target-ppc
subdirectory.
Then I found that Fabrice did a patch in virt_page_find_alloc for x86_64
support
(a few lines above in the same file).
I have to admit I just duplicated this hack and it solved my crashes.
As the address that generated the crash was 0xFFFFFFFFFFFFFFFC (-4), I
just admitted
that it would prevent the crash for any address...
I even did not check if the mask was the right one, in fact...

[...]

-- 
J. Mayer <address@hidden>
Never organized