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I've noticed some weird behavior when dual-booting Windows 7 and Windows XP:

As long as I'm rebooting from Windows 7, everything is normal.

However, if I boot into Windows XP and then boot back from XP into Windows 7, my boot process differs slightly:

  • The boot stage is slower (i.e. the stage with the glowing Windows logo takes about twice as long) -- Windows seems to be doing some more work every time I'm coming from XP.
    However, the extra time is CPU time -- the hard disk isn't accessed much during that time.

  • The login process is faster (as though everything was already loaded/prefetched)

  • Overall, the process is a bit slower.

My guess is that it has to do with something related to NTFS, but I really have no real evidence.

Does anyone know what triggers this? (I have Windows XP SP3 and Windows 7 x64 SP1.)

Update:

I just booted from Windows 8 back into Windows 7, and that also seemed to cause the delay...

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Not sure if this has any affect on booting W7 after XP...bertk.mvps.org/html/dualboot.html –  Moab Nov 12 '11 at 2:34
    
@Moab: That's a very interesting read, but yeah, it turns out that I've also disabled system restore and any backup/shadow-copy-related stuff on both OSes. –  Mehrdad Nov 12 '11 at 2:36
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Makes me wonder what other tampering XP is doing to the W7 installation though. –  Moab Nov 12 '11 at 4:23
    
@Moab: Haha yeah. If I had to hazard a guess, I would think it might be related to TxF -- maybe some log files are getting deleted or something, which causes Windows to check a bunch of stuff? But no idea really... –  Mehrdad Nov 12 '11 at 4:26
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Cold reboot initializes the hardware more thoroughly. For example, a warm reboot between Windows/Linux might show the wrong hour. Sometimes cold reboot is the only solution for such problems. –  harrymc Jan 9 '12 at 17:14

2 Answers 2

up vote 5 down vote accepted
+50

It seems like you are doing a warm reboot, while the dissimilarities between XP and 7 require a better initialization of the hardware adapters and registers, meaning a cold reboot.

Both boot modes are defined as follows:

Cold Boot (a.k.a. Cold Start) : Booting up from power-off condition.
Warm Boot (a.k.a. Warm Start) : Restarting the computer without turning the power off.

The Microsoft article Cold Booting Versus Warm Booting gives some hints :

A warm boot, accomplished by pressing the CTRL+ALT+DEL key combination, restarts the computer through the INT19h ROM BIOS routine. This warm-boot procedure usually does not go through the complete boot process; generally, it skips the power-on self test (POST) to save time. In addition, a warm boot frequently fails to reset all adapters in the computer's adapter slots.

To ensure that all adapters are properly reset, you should use the power switch to turn the computer off. Leaving the power off for ten seconds ensures that all the capacitors on the motherboard have time to discharge and should also give the hard disk drive a chance to stop spinning.

There is no complete list for all the adapters that are not reset for a warm boot. I know from experience that the clock is one of them, so that problems may occur when warm-booting between Windows and Linux which use the clock differently.

Apparently, such a difference also exists somewhere between XP and Windows 7 as well as 8.

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That Microsoft article was written for MS-DOS and DOS+Windows, as it says in it. The way that wholly protected mode operating systems, such as the two under discussion here, reboot under software control is rather different. –  JdeBP Jan 9 '12 at 18:29
    
@JdeBP: As I said, it gives a hint, which has to be extended to current technology. There wasn't much documentation on this to start with, and there is almost none actually. But the philosophy is still the same : warm boot does not reinitialize some adapters and circuits. The Windows/Linux boot problems I cited above are current. –  harrymc Jan 9 '12 at 18:37
    
Untrue. Any extension of that to current technology would be highly flawed, for the reasons I mentioned. And there's quite a lot of documentation on this subject, starting with the ACPI and EFI specifications and working through chipset datasheets and Intel architecture manuals to the PCI Local Bus specification. –  JdeBP Jan 9 '12 at 21:40
    
@JdeBP: The specs don't help here, because what Mehrdad is seeing should not happen. Warm boot is supposed mostly to only skip the POST. Evidently, Microsoft is skipping much more, maybe the full reinitialization of the disk controller, not respecting (again) the specs. –  harrymc Jan 10 '12 at 6:15
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@kinokijuf: Which doesn't make your "Windows doesn't use EFI" statement any more correct. After all, "Windows doesn't use BIOS; only the x86 versions do" –  grawity Jan 24 '12 at 10:55

The only logical conclusion I can come up with is the pagefile is managed differently between Windows 7 and XP, particularly the size allocated by the system.

Try configuring your system to not use a pagefile at all to test if this is indeed the problem.

Here below is an extract to support my theory.

Source

Page file size equal to RAM: Prior to Windows 7 the default paging file size was determined differently on different versions of Windows. But in general terms, when the paging file size was configured as “system-managed” its size would typically be calculated as RAM x (some number greater than 1) or RAM + (some number).

In Windows 7 and Server 2008 R2 the default size is equal to the amount of memory installed in the machine. Your gut reaction to this is probably the same as mine was – to get a successful complete memory dump the paging file needs to be a little larger than RAM. How much larger probably goes back to what version of Windows you are running and other factors, but 300 MB is generally considered plenty of padding for the purposes of getting a complete dump.

Below are links to help you disable the pagefile

Disable Pagefile in XP Disable Pagefile in W7

share|improve this answer
    
I'm already not using a pagefile for any of my operating systems. –  Mehrdad Jan 9 '12 at 15:22
    
@Mehrdad Maybe that’s your problem. –  kinokijuf Jan 24 '12 at 12:13
    
@kinokijuf: No it isn't. –  Mehrdad Jan 24 '12 at 17:12

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