John
Sun Jun 15 17:08:28 PDT 2008
You're welcome.
John
Oldster wrote:
> Thank you for that very full answer. I really appreciate it. Thanks again.
>
>
> "John John (MVP)" <audetweld@nbnet.nb.ca> wrote in message
> news:uxqW3QwzIHA.4004@TK2MSFTNGP03.phx.gbl...
>
>>Oldster wrote:
>>
>>
>>> As a subsiduary question... How does windows know which drivers to
>>>load in "safe" mode?
>>
>>It gets the information from the
>>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot Registry
>>key**. Also, before the kernel reads that key ntldr reads the registry
>>looking for device drivers with a start value of 0, telling it (ntldr)
>>that the device driver is to be loaded at boot time, typically these are
>>low level hardware device drivers, things like the keyboard, mouse, disk
>>and controller drivers, etc. The drivers with a start value of 0 are
>>"loaded" by ntldr but they are "started" by the kernel.
>>
>>** The HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot does
>>not exist when the computer is shut down, this key is created form one of
>>the numbered Control Sets when Windows is booted, so when booting to Safe
>>Mode the information will actually be retrieved from one of the numbered
>>Control Sets. We usually say that the information is obtained from the
>>Current Control Set because the information in the numbered Control Set
>>will be identical and it is easier for users to look at the
>>HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet to get the information
>>accurately, otherwise the HKEY_LOCAL_MACHINE\SYSTEM\Select key has to be
>>consulted to obtain the proper Control Set, see below for explanations
>>about the Select key.
>>
>>
>> > Or, for that matter,in "last good" mode?
>>
>>When you boot the computer and select a boot option ntldr reads the
>>HKEY_LOCAL_MACHINE\SYSTEM\Select key to determine which Control Set it
>>should load. The Select key contains the following values:
>>
>>Current
>>Default
>>Failed
>>LastKnownGood
>>
>>These values typically contains data as shown here:
>>
>>"Current"=dword:00000001
>>"Default"=dword:00000001
>>"Failed"=dword:00000000
>>"LastKnownGood"=dword:00000002
>>
>>The data may be different, if you have had failed boots you may have
>>different numbers (like 00000003) and the numbers assigned to the values
>>may be different than shown above. These numbers tell ntldr which Control
>>Set to load, the Control Sets are also held in the
>>HKEY_LOCAL_MACHINE\SYSTEM key, typically:
>>
>>HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001
>>HKEY_LOCAL_MACHINE\SYSTEM\ControlSet002
>>
>>When you boot the computer normally ntldr looks for the "Default" value
>>and loads the Control Set assigned to it, in the above example it would
>>load HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001, if you boot to Last Known
>>Good ntldr looks at, of course, the "LastKnownGood" value and loads the
>>corresponding Control Set.
>>
>>The Last Known Good set is only copied and recorded after a user
>>successfully logs on. In the above example, if you boot normally, Windows
>>will be booted using ControlSet001, after a user successfully logs on the
>>ControlSet001 will be copied to ControlSet002 and the control set number
>>will be recorded in the Select key. The value of the Select key and the
>>ControlSetnnn of the "LastKnownGood" configuration will not change until
>>the next successful logon. Booting successfully to Safe Mode does not
>>change the "LastKnownGood" Control Set, in only changes when booting
>>Windows normally.
>>
>>John
>
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