Re: [Qemu-devel] PowerPC64 and more

[Filip Navara <navaraf@reactos.com>]

J. Mayer wrote:

>On Fri, 2005-07-22 at 00:10 +0200, Filip Navara wrote:
>  
>
>>J. Mayer wrote:
>>
>>    
>>
>>>Here's a long awaited patch (hum, Fabrice ? ;-) ).
>>>It is really invasive in the target-ppc subdirectory.
>>> 
>>>
>>>      
>>>
>>[snip]
>>
>>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".

- Filip

>>Index: exec.c
>>===================================================================
>>RCS file: /cvsroot/qemu/qemu/exec.c,v
>>retrieving revision 1.60
>>diff -u -d -w -B -b -d -p -r1.60 exec.c
>>--- exec.c    24 Apr 2005 18:02:38 -0000    1.60
>>+++ exec.c    20 Jul 2005 23:00:26 -0000
>>@@ -257,6 +257,10 @@ static inline VirtPageDesc *virt_page_fi
>> {
>>     VirtPageDesc *p;
>> 
>>+    /* XXX: should not truncate for 64 bit addresses */
>>+#if TARGET_LONG_BITS > 32
>>+    index &= (L1_SIZE - 1);
>>+#endif
>>     p = l1_virt_map[index >> L2_BITS];
>>     if (!p)
>>         return 0;
>>    
>>
>
>  
>