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    |   xen-devel
RE: [Xen-devel] [PATCH]Do some checks and settings of CR0according to	VM 
| good point, and this is a two side issue, one is hardware 
capability, the other is software capability, maybe a better way is to have 
another CR0 value expected by software, and use both of hardware and 
software expected value to get the effiective one? -Xin 
 
  
  I agree with some aspects of this patch but not 
  others. For example, not explicitly including PG and PE in guest-mode cr0 
  value is a bad idea. If a future processor does support e.g., paged real mode 
  then it won’t magically be the case that old Xen will know how to handle that. 
  Currently we expect and require a VMX guest always to run with 
  CR0.PE==1.
 I’ll pull out the bits of the patch that I 
  like.
 
 -- Keir
 
 On 27/7/07 09:03, "Liu, Eric E" 
  <eric.e.liu@xxxxxxxxx> wrote:
 
 
 According to SDM Vol 3B 19.8 Software should consult 
    the VMX capability MSRs to determine how bits in CR0 are set, VMXON 
    fails if any of these bits contains an unsupported value. And according to
 SDM Vol 3A 2.5, 3B 21.3 and 2A MOV-MOV to/from Control Registers, 
    setting upper 32 bits of CR0
 results in a general-protection exception 
    and setting the reserved bits in lower 32 bits of CR0 are ignored .
 In 
    accordance with above-mentioned, the patch is attached to do some checks and 
    settings of CR0.
 
 
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