Best Answer Tripredacus , 24 April 2013 - 02:33 PM
Win7 and Win8 UEFI can be very fast, less than 10 seconds but depends on the hardware. Some newer systems have a "fast boot" as an option in the BIOS. On these systems, boot can be so fast that it seems humanly impossible to get the F8 boot menu to work! And when I saw UEFI, I mean using a GPT disk. As I mentioned, I have done no testing on boot times with an MBR disk with UEFI enabled because its out of scope for what I do.
WinPE booted in legacy BIOS mode can set a GPT disk if the hard disk is less than 2TB. If you are using a 3TB disk and convert to GPT you will only be able to make a 2TB volume. Also, BCDBoot cannot write boot files to the disk in this case whether using GPT or MBR (only applicable if using multiple partitions).
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Member
Posted 19 April 2013 - 06:00 AM
is it possible to
#1 uefi bios -> uefi boot -> SYSLINUX menu -> select win7pe (or maybe ?win8pe?) boot.wim -> install win7 uefi?
#2 in order for win7 uefi must the disk be GPT? can it be MBR?
#3 yeah that got me thinking, can i use win8pe legacy (pxeboot from syslinux) to install win 7 (legacy)? could possibly solve some of the broadcom driver issues i was having with win7pe.
Edited by biatche, 19 April 2013 - 06:02 AM.
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Posted 19 April 2013 - 01:57 PM
I don't know about syslinux, since my syslinux menu is only set for BIOS boot... but
A WinPE3 (Windows 7) can deploy Windows 8... well probably... but you need to copy in the DISM.exe from Win8 or WinPE4. Then again, your other question, YES WinPE4 can deploy Windows 7 no problem.
For UEFI, the WinPE you make must be 64bit version!
Regarding GPT disk, You can do GPT on a UEFI boot (of course) but you can only do a MBR disk if your deployment has the OS on the first partition (BCDBoot might not work). I don't think there is a problem using GPT every time tho, even on disks that are less than 2TB.
Member
Posted 19 April 2013 - 02:11 PM
I don't know about syslinux, since my syslinux menu is only set for BIOS boot... but
A WinPE3 (Windows 7) can deploy Windows 8... well probably... but you need to copy in the DISM.exe from Win8 or WinPE4. Then again, your other question, YES WinPE4 can deploy Windows 7 no problem.
For UEFI, the WinPE you make must be 64bit version!
Regarding GPT disk, You can do GPT on a UEFI boot (of course) but you can only do a MBR disk if your deployment has the OS on the first partition (BCDBoot might not work). I don't think there is a problem using GPT every time tho, even on disks that are less than 2TB.
So wait, i use tftpd32, how can i make uefi boot into UEFI pxe boot menu? ok perhaps no one is able to yet. so moving on..
Yes I already have a running x64 Win7PE (bios boot via syslinux pxeboot menu) that installs windows 7 x64 all well and fine.
So it's ideal if i can boot into win7pe x64 via legacy pxe and later on set uefi boot..
Right now, I wish to switch to Win7 x64 UEFI+MBR. By default, a 100MB partition is created... i have a hack that makes it so that it doesnt' create this 100MB partition.. if this is helpful info.. So what do I actually need now? Can I install win7 x64 as normal and then set as UEFI later on?
Frequent Member
Posted 22 April 2013 - 03:23 PM
I need to say my PXELinux boots off WDS in Server 2008 R2. 
Its not so much a hack to install Windows on MBR disk without the System Reserved partition. All my basic unattends install this way by default.
There are two things regarding the "switching" ...
1. I recall in testing that Windows *sometimes* had no problem if you switched the UEFI boot setting in the BIOS. I do not recall the exact circumstances (I was not testing this ability) but Windows didn't seem to mind.
2. If you mean changing the disk to GPT, this won't work. For example, if you try to convert a disk to GPT that already has an MBR partition on it, Diskpart will give an error.
My setup for UEFI PXE booting is on WDS on Server 2012. I have success in booting now but I am in the development stages and have not done any actual deployments yet.
Member
Posted 22 April 2013 - 03:31 PM
1. OK I'll try test and see if a w7 x64 on legacy bios now can be made to boot via uefi. If it does i don't need to trouble myself too much.
2. I do not plan on changing on GPT irregardless of circumstances. It will be MBR all the way. What I want is for UEFI to boot off MBR (and have the "UEFI" fast boot). All I want from UEFI is the fast boot, I don't know of any other feature that benefits me.
3. Can I have UEFI PXE boot (hm, I don't have Server 2012 and I won't be using WDS) and Legacy PXE (tftpd32) running concurrently? Would serve me ideally if I can run a UEFI pxe server as well as tftpd32 on the same server and hvae UEFI pxe boot into Win8PE directly. What do you know?
Frequent Member
Posted 23 April 2013 - 02:31 PM
No the partition requirements are different for Windows 7 to boot in UEFI. Even if you had MBR disk and changed to UEFI mode, I don't know if you'll be able to see the faster boot.
http://technet.micro...1(v=ws.10).aspx
IMO the only reason why you would need to do UEFI PXE boot is to deploy GPT images, or if the hardware has no BIOS level capability (have yet to see that btw) ... WinPE doesn't boot any faster in my experience when booting UEFI vs BIOS/legacy mode.
Member
Posted 23 April 2013 - 03:55 PM
So ...
in terms of boot times..
(Win7 Legacy MBR == Win7 UEFI MBR == Win7 UEFI GPT) > Win8 Legacy MBR > (Win8 UEFI MBR = Win8 UEFI GPT)
longer boot times ..................................................................................................shorter boot times
1. Is this right?
(and so.. improvising...)
2. Can Win8PE (booted via Legacy PXE) install Win8 UEFI MBR or Win8 UEFI GPT (or otherwise do MBR/GPT installation via Legacy) and then later set to UEFI boot?
Overall, I'm only interested in speed. I won't be deploying any images, but I will be installing windows via script via WinPE which is currently booted via iPXE (which i finally got working!).
Frequent Member
Posted 24 April 2013 - 02:33 PM Best Answer
Win7 and Win8 UEFI can be very fast, less than 10 seconds but depends on the hardware. Some newer systems have a "fast boot" as an option in the BIOS. On these systems, boot can be so fast that it seems humanly impossible to get the F8 boot menu to work! And when I saw UEFI, I mean using a GPT disk. As I mentioned, I have done no testing on boot times with an MBR disk with UEFI enabled because its out of scope for what I do.
WinPE booted in legacy BIOS mode can set a GPT disk if the hard disk is less than 2TB. If you are using a 3TB disk and convert to GPT you will only be able to make a 2TB volume. Also, BCDBoot cannot write boot files to the disk in this case whether using GPT or MBR (only applicable if using multiple partitions).
Member
Posted 24 April 2013 - 02:47 PM
OK Thanks, I can improvise and work my way from here.
But I guess UEFI iPXE WINPE has a long way to go
Frequent Member
Posted 27 January 2014 - 09:38 PM
Windows NEEDS MBR for BIOS
GPT for UEFI
GPT is FAR better than MBR, and there exist tools like gptgen which can convert existing MBR disk to GPT. It's a more sane layout, not with arbit limitations of 4 partitions, with one having to be extended, and then THOSE having their own glue boot records.....
I am actually looking for GPT on BIOS systems... some way to hack bootmgr probably.
The speed increase is ENTIRELY due to UEFI. MBR and GPT no difference for this....
WinVBlock Dev
Posted 31 January 2014 - 01:26 AM
That's quite a general claim. Prove it.The speed increase is ENTIRELY due to UEFI. MBR and GPT no difference for this....
Frequent Member
Posted 02 February 2014 - 08:58 AM
Edited by milindsmart, 02 February 2014 - 09:00 AM.
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