Howto: Dual-Booting Vista Home and Solaris

Question

Hello.
I searched a lot of forums about this but found nothing. I finally managed to install Solaris on a computer running Windows Vista Home and post my experiences here for people having the same problem.
Known problem: When the MBR of a hard disk is altered (e.g. installing additional operating systems) Windows Vista will not boot any longer.
Reason: Windows Vista uses a checksum of the MBR. If the checksum is not correct it does not boot.
How can you install Solaris anyway?
I did it using the following steps (requires some C programming skills and a C compiler for Windows):
a) Make a copy of the MBR (e.g. by booting the Solaris DVD into the single user shell) onto an USB stick:
dd if=/dev/rdsk/cxtxdxp0 of=/usbdisk/origmbr bs=512 count=1b) Create the Solaris partition and install Solaris
c) Make a copy of the new MBR. This is done the same way as step "a)". Replace "origmbr" by "newmbr".
d) Restore the original MBR. This is done like step "a)" but "if=" and "of=" must be turned around (of=/dev ... if=/usbdisk ...).
(This causes the Solaris partition to be removed; you will not see it in fdisk any more; but do not panic - the data is not deleted)
e) Reboot - Vista will be booted
f) Write the new MBR to the disk. This is where you need a C program. The program must be executed using administrator rights:
#include <windows.h>
#include <stdio.h>
main()
    HANDLE h;
    FILE *f;
    DWORD d;
    char a[512];
    h=CreateFile("\\\\.\\PhysicalDrive0",GENERIC_WRITE,0,0,
        OPEN_EXISTING,0,0);
    // Replace newmbr by the actual file name of the file
    // containing the new MBR
    f=fopen("newmbr","rb");
    fread(a,1,512,f);
    fclose(f);
    WriteFile(h,a,512,&d,NULL);
    CloseHandle(h);
}I also took bytes 0...0x1BD from the original MBR and only bytes 0x1BE...0x1FF (actual partition information) from the new MBR because I heared that Vista does not work with foreign MBR boot loaders.
g) Go to the computer administration (right-click of "Computer" in the start menu) and "administration" and go to the volume manager. Press F5 - now the volume manager will see the Solaris partition. Make any partition the active partition and change the active partition back to the Windows partition - now the checksum of the MBR will be re-calculated.
I do not know if this step is necessary because "diskpart.exe" should also re-calculate the checksum.
h) Start diskpart.exe with administrator rights. Make the Solaris partition (containing Grub) the active partition - now the computer boots GRUB and Vista can be booted.
Note:
The boot information in the system control as well as bcdedit.exe will only work if the Windows partition is active. Maybe the system recovery will also not work.
Martin

Answer 1

Hello.
The main problem is not the fact that GRUB does not boot - this could be easiely solved by overwriting the MBR by the original MBR (so changing from Windows to another OS must be done using a bootable CD or disk).
The problem is that creating an additional partition is not possible. I think if Microsoft wanted to "solve" this "problem" (forbid other OSs to be booted) they were not able to do this because many modern BIOSes create a hard disk partition for their data (e.g. hard disk encryption, finger print stuff etc.). Windows would either not be able to boot on such machines (not wanted by Microsoft) or not be able to recognize that another OS is installed (that can be booted at least by using a boot CD).
I think that Microsoft themself have no interest in forbidding other OSs to be booted. There are a lot of machines running Windows only as secondary OS (e.g. in airspace industry). Microsoft is not interested in not being able to sell a newer version of Windows to owners of these machines.
Martin