RE: [Xen-devel] Switching from writeable pagetable toshadowlog-dirtyat runtime

[Khoa Huynh <khoa@xxxxxxxxxx>]

"Xin, Xiaohui" <xiaohui.xin@xxxxxxxxx> wrote on 10/14/2005 04:43:07 AM:

>
> Keir,
> We found that in 32-bit code, the shadow_fault() do one more thing
> than 64-bit code.
> The following code in file shadow32.c checks the L1 page table with
> RW bit removed and make the shadow with RW bit, it does not inject
> the fault to guest.
> Does this is a work-around for switch from writable pagetable to
> shadow mode enable?
> Does this code makes sense to the writeable pagetable, and then may
> be one reason that 32bit log-dirty code can work?
>

I don't think we use log-dirty shadow mode - at least when setting up
VMX domains; we only use shadow translate and external modes.  See
vmx_final_setup_guest() in xen/arch/x86/domain.c.  I searched through
the code for 32-bit x86, and I don't recall ever seeing this log-dirty
mode be enabled.  When should we use log-dirty shadow mode ?
Thanks.

Khoa


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