6 replies to this topic

[ilko]

I am trying to launch Grub4DOS either by changing in NT bootsector NTLDR to GRLDR, or by renaming GRLDR to NTLDR. Both ways fail.
USB stick formated by HP USB format utility and PEtoUSB. Tried all format options- FAT16, 16X, 32, NTFS.
Grub4Dos versions 14-03-2008 , 0.4.3 from 10.2007 and the stable 0.4.2.
Using various format options result in either blinking cursor, "please remove disk or other media", "FATAL INT18:BOOT FAILURE" in QEMU, or starting from the second disk.
Tests on Dell Inspiron 6000 and QEMU.
In all formatting options using ntldr or setupldr.bin, bootmgr renamed to ntldr start fine.

Am I missing something, or simply GRLDR cannot be started from NT bootsector ? As far as I remember there were posts on 911cd.net describing success renaming GRLDR to NTLDR, I never had such on my machines.

Reading README_GRUB4DOS.txt description of GRUB-bootable bootsector doesn't help me much to get the details what is wrong.
I'd like to avoid using bootlace.exe or grldr.mbr to start directly grub4dos, as well as using NTLDR/boot.ini to chainload GRLDR.

What would be the easiest way to format USB stick and make it GRUB4Dos bootable considering the written above?

ilko

[tinybit]

If you do want it like that, be aware there are limitations on it:

1. The fstype should be FAT32 or NTFS. Others will fail, or supposedly will fail.

2. The boot record should come from Microsoft. Note that both FAT32 and NTFS have multi-sector boot record with Microsoft. For both FAT32 and NTFS, you had better try the windows 2000 boot record, which is considered tidy and harmless.

------------

Optionally, you may try it in another way: installing grldr filesystem boot record onto any of FAT12/16/32/NTFS/ext2/ext3 and changing all occurences of grldr/GRLDR into ntldr/NTLDR.
You may do it manually(or thru bootlace.com). See readme for descriptions on the layout of grldr boot record for FAT/NTFS/EXT2. In that way, the GRLDR boot code will become the NTLDR boot code. Thus you can place in the root dir either the MS NTLDR or the NTLDR renamed from GRLDR.

[ilko]

Thanks Tinybit, FAT32 indeed made a difference.

Another issue turnd out to be in HP USB format tool v2.1.8- it does NOT set an active partition, no matter of FS type. Writing zeros to first 500 sectors prior to formatting doesn't change this behavior, nor did multiple formats.
2.0.6 works just fine, GRLDR renamed to NTLDR starts when FAT32 was used.
Used 1GB USB stick for tests.
Format FAT32 from Windows Explorer, while stick seen as removable- by default it won't boot. Drive ID in bootsector is 00h, change it to 80h- it boots, GRLDR renamed to NTLDR works fine.
USB stick seen as fixed, using Hitachi microdrive filter driver, formated FAT32 from windows explorer. It won't boot. Drive ID is 80h, but in MBR there is no active partition. Change Boot Indicator at offset 1BE to 80 and it boots, GRLDR renamed to NTLDR.

FAT16 format by HP tool, PEtoUSB or XP format results in GRLDR won't start when renamed to NTLDR. Just of curiosity- why it doesn't like FAT16?

ilko

[tinybit]

why it doesn't like FAT16?

Because the MS NTLDR boot sector of an FAT12/16 partition only loads one sector, i.e., the first sector of the NTLDR file. If this NTLDR was our GRLDR, then this will fail to boot. On the other hand, the MS NTLDR boot sector of an FAT32/NTFS partition will load the whole NTLDR file into memory, and thus our GRLDR(renamed to NTLDR) can boot OK.

[ilko]

Thanks, now it's all clear

[was_jaclaz]

Thanks, now it's all clear

Well, NO, it it is not, there is some mixing between FAT16 and FAT32.

Maybe this it is (provided I got it right):

FAT16 bootsector will NOT work

FAT32 and NTFS bootsectors WILL work

jaclaz

[tinybit]

Oh, yeah. I just corrected my post.

FAT12/16 bootsector will NOT work

FAT32 and NTFS bootsectors WILL work

Those are true for MS NTLDR boot record.

If our grldr boot records are employed, all of FAT12/16/32/NTFS/EXT2/EXT3 will be fine, as mentioned above.