[joakim]

No, not except preventing an insignificant waste of resources. That's why I said only consider it as a PoC.

Joakim

[Metzen]

joakim, on 26 August 2010 - 11:54 PM, said:

No, not except preventing an insignificant waste of resources. That's why I said only consider it as a PoC.

Joakim

Not true.

A smaller file size can help speed up PXE booting over a slow link. Sometimes I have to work with a link that takes ~30mins to boot WinPE over PXE. Any reduction is a huge boon!

In addition, a smaller boot.sdi will kick off downloading the WIM faster as well.

[joakim]

Yes I am aware of the pxe fact, but such slow links are getting rather unusual nowadays I think.

If this boot.sdi will help then very good to hear. But keep in mind it has not been extensively tested. I cannot guarantee that it works in any environment.

If you run into problems with it, let me know.

Joakim

[joakim]

If someone with very good knowledge about the $LogFile is aroung here, then please join this thread. If we could decode the structure of that metafile (or just the header of it), then I am quite sure boot.sdi could be reduced close to 60 Kb.

Joakim

[rpaz]

Hi Joakim,

Thanks for sharing this small boot.sdi file it works fine booting PE2 and PE3 images from a PXE server.

Every size reduction is good to make PXE boot faster.

[joakim]

I just realized how to create/modify tiny NTFS partitions with the standard tools like chkdsk.exe and format.com. Actually it must be the exact same thing that Mark did back in the 90's when he made the ntfs floppy thing. He said he used SoftIce back then, but it can also easily be done by simply patching untfs.dll. The whole point is to set the size of the $LogFile to something below the hardcoded minimum (2097152 bytes or 2 Mb), and thus significantly reduce the size of the metafiles/systemfiles. Now after some tests, it seems no coincidence that Mark ended up with a 256 Kb logfile. I believe it's a driver limitation.. So 256 Kb seems the smallest possible size that will be accepted by the nt file system driver. Smaller logfiles can be made (48 Kb) with correctly adjusted $MFT++ entries, but the actual header of the logfile (restart page) gets invalidated.

3 places need modification;

At va 5b04cfc5;

[b8 00 00 20 00] -> [b8 00 00 04 00]

At va 5b04d324;

[c7 00 00 00 20 00] -> [c7 00 00 00 04 00]

At va 5b04d336;

[bf 00 00 20 00] -> [bf 00 00 04 00]

And if you also want to try it on a floppy then at va 5b0346fb;

[74 08] -> [eb 08]

But for already known reasons, the ntfs driver cannot open such a floppy, even though its correctly ntfs formatted..

This was done on the XP sp2 version of untfs.dll (5.1.2600.2180). Just make the mod and place it together with chkdsk/format in a separate directory.

Now you can create NTFS partitions below 1 Mb in size (with limited usage though).

Note:
Some highly advanced tools like Paragon Hard Disk Manager do not even evaluate the validitiy of the actual $Logfile, so it will report a damaged NTFS partition (seen as RAW by Windows) to be 100% healthy...

Joakim

[allen2]

Did you used

chkdsk /l:size

to set the wanted size as described there ?

[joakim]

That is the way if you only want to adjust the size of the logfile. However, you cannot set it to lower than 2 Mb (because it's coded so), unless you are using a patched untfs.dll. If you run;

chkdsk /f driveletter

,it will create a new logfile with default size of 256 Kb (as well as fixing other issues). If you run format.com to format a partition with NTFS with the patched untfs.dll in the same directory, then it will also default to 256 Kb for the logfile. Of course this is not something one would do on a multi GB partition. This is mostly for the sake of the fun in exploring the filesystem.

In the patch posted above 200000h = 2097152 bytes = 2 Mb, while 40000h = 262144 bytes = 256 Kb. So adjust the values to whatever (but at least a multiple of 2 of 40000h).

Joakim

This post has been edited by joakim: 07 April 2011 - 02:01 PM

[joakim]

I have been informed that the newest Windows 8 (6.2.8250) does not work with my minimal boot.sdi. It is likely something in bootmgr that has changed, so one of the files needs to be changed. Will start by looking in bootmgr. Other stuff I should look at while inside it?

[joakim]

After a little look inside bootmgr (and boot.sdi) it seems like the issue is with the way the wim format is mounting and how the filesystem driver (ntfs) sees the mounted volume. So bootmgr does its job, and the wim is mounted, and winload and the kernel is then executed all fine. However the crash (or freeze) happens when the kernel is loading drivers (have not debugged yet). So I'm not sure what needs to be changed. I managed to reassemble a modified bootmgr version 6.2.8250, so at least something useful came out of it.

[joakim]

Grabbed one of my older 900 Kb versions and that booted fine, so I presume Windows 8 needs some "free space" inside the tiny partition to be happy wimbooting.

[Kullenen_Ask]

can you upload your older 900kb versions for release preview?

[joakim]

I am not sure if it was this one I used for the test; http://www.mediafire...8lxw24t00xaaef6 (960 KB) but it may look so. It was never handcrafted the way 300KB version was, so can probably be shrinked a bit more. I just don't have the time for that now, but you are free to give it a try. It's a nice exersice

[Kullenen_Ask]

It works. As i see, you use volume names for advertising. 300kb one was "joakim" and this one is "tiny". I understand such behaviour but if it can stay unchanged i will be appreciate. You can embed somewhere in file as it can be seen with hex editing or any other way. Anyway i can live with it. thx.

[jaclaz]

Kullenen_Ask, on 13 June 2012 - 11:19 AM, said:

As i see, you use volume names for advertising. 300kb one was "joakim" and this one is "tiny".

I can understand the "advertising" mesage possibly conveyed by "joakim", but I am completely failing to see the one in "tiny"

jaclaz

[joakim]

Hmm, I can't remember if I put in some messages. Either way, I'm preatty sure they won't make any difference to you when booting Don't worry be happy.

[Kullenen_Ask]

it makes difference when using winpe. not important in a windows setup dvd

[joakim]

Kullenen_Ask, on 13 June 2012 - 01:42 PM, said:

it makes difference when using winpe. not important in a windows setup dvd

Did I miss something here? Please explain what makes a difference and how.

[Kullenen_Ask]

Under winpe i frequently working with drives. File resque operations. I will see that drive name lots of and will think you more than your girlfriend.

[hlstudio]

great job!