10 replies to this topic

[favorinus]

Hi,

 

I am trying to boot a VHD in ramboot modus, but no luck so far :-(

 

I am using grub4dos for UEFI.

ubs stick = 64 gb. with two mbr paritions.  100 mb fat32 (efi / grub) + 64 gb ntfs containing the vhd file

 

 

title 22gb.vhd 

load /EFI/grub/ntfs_x64.efi

find --set-root --ignore-floppies --ignore-cd /22gb.vhd

map --mem --top /22gb.vhd (hd)

chainloader (hd-1)

 

 

Error 21: Selected disk does not exist

 

 

the vhd file is loading into memory but then error 21  ...

 

ps: 22gb.vhd = 2.2 GB in size, not 22GB 

[steve6375]

what happens if you do not load the ntfs_x64.efi driver?

What is the ntfs_x64.efi file? Where is it from? Why is it needed?

Edited by steve6375, 19 October 2022 - 09:04 AM.

[favorinus]

Hi,

 

I don't know why it's needed. It is also not working without it and sometimes I see that line on this forum. The file I found on some website. but it's not working without that line either. 

 

I use grub4dos for UEFI 2022-09-15

 

any idea why I get this error 21 ?

[steve6375]

Those commands work for me.
I suggest using the command line
and typing in just the map command and the chainloader command
Then try an ls command to see if you can list the file.
Maybe you have a bad or fake usb drive?
If it all looks ok, type boot after the chainloader command and see if it boots

[favorinus]

ok,

 

now I try another vdh file (two partition fat32 and ntfs)

 

in the commandline :

 

find --set-root /Win10_4125.vhd (hd)

 

: --> (hd0,1)

ls gives me the second partition of the pendrive (ntfs)

 

map /Win10_4125.vhd (hd)

--> grub says nothing

ls lists the same: the second partition of the pendrive

 

chainloader (hd-1)

--> grub says nothing

ls the same partition

 

boot 

--> it's booting the bcd that is on the first partition of the pendrive.  

[steve6375]

OK - but no error 21?

Also the command you used before included  --mem --top  

Did you try that?

[favorinus]

Win10_4125.vhd does not fit into memory.

 

in the commandline :

 

find --set-root /22gb.vhd (hd)

 

: --> (hd0,1)

ls gives me the second partition of the pendrive (ntfs)

 

map --mem --top /22gb5.vhd (hd)

--> it's loading when it's done: error 21. selected disk does not exist

[steve6375]

How much RAM is in your system?

 

maybe it failed to load as it is such a large file

[favorinus]

it has 8gb, the file is 2.2 gb.  

 

without --mem is the same error btw. 

 

erorr 21.

 

the vol command strangly says it's on (hd1,0) after mapping

[steve6375]

Try without --top
Try in virtual machine
Try smaller vhd
Upload test vhd so we can test

[alacran]

Hi,

 

I am trying to boot a VHD in ramboot modus, but no luck so far :-(

 

I am using grub4dos for UEFI.

ubs stick = 64 gb. with two mbr paritions.  100 mb fat32 (efi / grub) + 64 gb ntfs containing the vhd file

 

 

title 22gb.vhd 

load /EFI/grub/ntfs_x64.efi

find --set-root --ignore-floppies --ignore-cd /22gb.vhd

map --mem --top /22gb.vhd (hd)

chainloader (hd-1)

 

 

Error 21: Selected disk does not exist

 

 

the vhd file is loading into memory but then error 21  ...

 

ps: 22gb.vhd = 2.2 GB in size, not 22GB 

 

Let's start for the beginning, General Guide:

 

1 - Before trying Ramboot first make sure your VHD boots fine as Filedisk.

 

2 - SVBus driver is required for Ramboot.

 

Did you installed SVBus driver before tying to Ramboot from the VHD?

 

3 - Is your VHD installed in Compact or Wimboot mode?

 

This is important ONLY for MBR Rambooting a VHD installed in Wimboot mode from a USB device, it has to be mapped as (hd-1), not as (hd) as it does in all other cases and also when the Wimboot installed VHD is located into the internal HD, this especial requirement doesn't apply in UEFI environment.

 

4 - load /EFI/grub/ntfs_x64.efi  >>> is only required in single partition (NTFS) VHDs when booting on a PC that its UEFI Bios lacks NTFS drivers, so if your VHD has a FAT-32 active primary partition (where all boot files and folders reside) + an NTFS partition (where OS is installed), this is not required.

 

alacran