* PAE is_guest_l2_slot()
@ 2006-09-12 14:00 Jan Beulich
2006-09-12 14:25 ` Gerd Hoffmann
0 siblings, 1 reply; 4+ messages in thread
From: Jan Beulich @ 2006-09-12 14:00 UTC (permalink / raw)
To: xen-devel
Could anyone help me understand what the meaning of the hardcoded 3 in that
macro is? With PGT_va_mask being an 11-bit mask I can't seem to make any sense
of this.
And while at this, for 64-bits PGT_va_mask is defined as a 28-bit mask, but the
comment there as well as my calculations say this should be only 27 bits.
Thanks, Jan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: PAE is_guest_l2_slot()
2006-09-12 14:00 PAE is_guest_l2_slot() Jan Beulich
@ 2006-09-12 14:25 ` Gerd Hoffmann
2006-09-12 14:30 ` Jan Beulich
0 siblings, 1 reply; 4+ messages in thread
From: Gerd Hoffmann @ 2006-09-12 14:25 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel
Jan Beulich wrote:
> Could anyone help me understand what the meaning of the hardcoded 3 in that
> macro is?
xen address space window is in l2 table #3 (of 4) ...
cheers,
Gerd
--
Gerd Hoffmann <kraxel@suse.de>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: PAE is_guest_l2_slot()
2006-09-12 14:25 ` Gerd Hoffmann
@ 2006-09-12 14:30 ` Jan Beulich
2006-09-12 14:51 ` Gerd Hoffmann
0 siblings, 1 reply; 4+ messages in thread
From: Jan Beulich @ 2006-09-12 14:30 UTC (permalink / raw)
To: Gerd Hoffmann; +Cc: xen-devel
>>> Gerd Hoffmann <kraxel@suse.de> 12.09.06 16:25 >>>
>Jan Beulich wrote:
>> Could anyone help me understand what the meaning of the hardcoded 3 in that
>> macro is?
>
>xen address space window is in l2 table #3 (of 4) ...
That's why I pointed out that the mask is 11 bits (not 2) - what you say would mean
that the constant should be 0x600 (the top 11 bits of such a va), and comparison
should be >= rather than ==.
Jan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: PAE is_guest_l2_slot()
2006-09-12 14:30 ` Jan Beulich
@ 2006-09-12 14:51 ` Gerd Hoffmann
0 siblings, 0 replies; 4+ messages in thread
From: Gerd Hoffmann @ 2006-09-12 14:51 UTC (permalink / raw)
To: Jan Beulich; +Cc: xen-devel
Jan Beulich wrote:
>>>> Gerd Hoffmann <kraxel@suse.de> 12.09.06 16:25 >>>
>> Jan Beulich wrote:
>>> Could anyone help me understand what the meaning of the hardcoded 3 in that
>>> macro is?
>> xen address space window is in l2 table #3 (of 4) ...
>
> That's why I pointed out that the mask is 11 bits (not 2) - what you say would mean
> that the constant should be 0x600 (the top 11 bits of such a va), and comparison
> should be >= rather than ==.
IIRC the full 11 bits are needed for L1 tables only (2 indexing into L3
and 9 indexing into L2). Has been quite some time I looked into this
code ...
cheers,
Gerd
--
Gerd Hoffmann <kraxel@suse.de>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-09-12 14:51 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-09-12 14:00 PAE is_guest_l2_slot() Jan Beulich
2006-09-12 14:25 ` Gerd Hoffmann
2006-09-12 14:30 ` Jan Beulich
2006-09-12 14:51 ` Gerd Hoffmann
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