Increasing success rate from about 95% to nearly 100%

[Cosmin3]

Problem with another computer, this time a notebook.

I apologize for the bad quality of the image but since I don't have a camera I was lucky that the guy had one...

In Bios I set USB HDD as first boot device, internal HDD as the second.

In attachment is the report.

Report.zip

[jaclaz]

That screenshot says that grub4dos grldr.mbr attempted finding grldr in:

• first hard disk (hd0) : only 1 primary partition : (hd0,0)
  
• second hard disk (hd1): (1 primary (hd1,0) and 1 Logical Volume inside Extended (hd1,4)
  

and could not find it.

The second disk (hd1) is the internal one and there isn't actually a grldr in it, right?

In the relevant part of the "report":

Partitions:

C: (NTFS) 76308 MB (69383 MB free)

D: (NTFS) 76308 MB (75474 MB free)

E: (NTFS) 465.8 GB (413.5 GB free)

Total Size 614.8 GB (555.0 GB free)

Which one is the USB HDD?

If E: it means that there might have been a misunderstanding till now.

grub4dos right now WILL NOT work with some BIOSes on partitions bigger than the LBA28 limit because the BIOS (in the USB part only) does not support LBA48.

It is not a "fault" of grub4dos, simply the BIOS sends it some "incorrect" data

You need to have a partition BELOW that limit, otherwise, each time you will find one of these BIOS you will have this same problem.

jaclaz

Edited January 25, 2011 by jaclaz

[Cosmin3]

It's E.

Ok.

The guy has a 2 GB stick with a single primary partition on it.

I made it bootable with grub4Dos and I asked him to restart the computer (I was talking on the phone with him and I entered on his computer with TeamViewer).

He said there are a bunch of white messages on black screen (he doesn't know much about computers).

I asked him to press Space when it says that and after a couple of restarts succeeded.

From what he was reading to me it's the same problem.

Edited January 25, 2011 by Cosmin3

[jaclaz]

Ok.

The guy has a 2 GB stick with a single primary partition on it.

HOW it is set?

"Fixed" or "Removable" (I will tell you, without teamviewer, only through my crystal ball, that is "Removable" )

I made it bootable with grub4Dos and I asked him to restart the computer (I was talking on the phone with him and I entered on his computer with TeamViewer).

But you did not re-partitioned/formatted it with RMPREPUSB.

On some BIOSes of the "bad BIOSes" group, it has been found that an entry for a (fake) second partition is needed for the BIOS to map the device as "Hard Disk" with USB sticks marked as "Removable".

He said there are a bunch of white messages on black screen (he doesn't know much about computers).

I asked him to press Space when it says that and after a couple of restarts succeeded.

From what he was reading to me it's the same problem.

It may also be a completely different problem.

Succeeded in WHAT?

How EXACTLY was grub4dos installed?

What EXACT version of grub4dos was tested?

The space bar is normally the hot-key to boot the grub4dos MBR before the "previous MBR".:

	--hot-key=K		if the desired key K is pressed, start GRUB
				before booting PREVIOUS MBR. K is a word
				value, just as the value in AX register
				returned from int16/AH=1. The high byte is the
				scan code and the low byte is ASCII code. The
				default is 0x3920 for space bar. See "int 16
				keyboard scan codes" below.

It should only make sense if --boot-prevmbr-first was used.

	--boot-prevmbr-first	try to boot PREVIOUS MBR before the search for
				GRLDR.

	--boot-prevmbr-last	try to boot PREVIOUS MBR after the search for
				GRLDR.

It could be a timing problem of some kind? (but it doesn't make much sense, a stick has no delay in access, and anyway, IF the usual Try (hd0,0): .... etc. was shown, access to the device was available).

Unfortunately "a bunch of lines" is again not a good enough description/report.

jaclaz

[karyonix]

I managed to generate a error in VirtualBox.

I don't know if it's normal or not to show it...

How can you do this: attach 2 HDD; Primary master should be with something else like Windows XP, Primary slave should have Grub4Dos in MBR.

Start the virtual machine and press F12 to show boot menu.

Choose 2 (for the second HDD).

The virtual machine freezes with the message "Missing MBR helper". Oh, the second HDD didn't have a MBR when I used grub4Dos Gui to add one.

It is VirtualBox BIOS bug.

1. Normally, BIOS writes number of hard disk drives to memory at address 0x475. In VirtualBox this byte is always 1, no matter how many disk is installed. This is bug.

2. When you select non-first hard disk in BIOS boot selection menu, in most (all?) PCs I have tried, the selected drive gets drive number 0x80 and other drives get 0x81,0x82 ... .

In VirtualBox, the selected drive have the same drive number as when it is not selected. If you select second hard disk, it gets drive number 0x81.

This can be considered non-bug, just different behavior.

1+2 together : You cannot boot GRUB4DOS from second drive.

Workaround : Don't use F12 and 2. Change drives order in Settings storage page.

Edited March 2, 2011 by karyonix