Hi, I am trying for dual boot with solaris and linux.
I have installed rh4u4 successfully. through fdisk I selected a partition[sda2 below] and changed the label to bf, for solaris.

sda1 - rh4u4
sda2 - sol10
sda3 - linux swap

I have successfully installed solaris now on sda2.

my grub file snip in solaris is :

# kernel /platform/i86pc/multiboot <boot-args> -B prop1=val1,prop2=val2,...

#

#---------- ADDED BY BOOTADM - DO NOT EDIT ----------

title Solaris 10 8/07 s10x_u4wos_12b X86

kernel /platform/i86pc/multiboot

module /platform/i86pc/boot_archive

#---------------------END BOOTADM--------------------

#---------- ADDED BY BOOTADM - DO NOT EDIT ----------

title Solaris failsafe

kernel /boot/multiboot kernel/unix -s -B console=ttya

module /boot/x86.miniroot-safe

#---------------------END BOOTADM--------------------

title RH4u4

rootnoverify (hd0,0)

chainloader +1

makeactive



# Unknown partition of type 131 found on /dev/rdsk/c0t2d0p0 partition: 1

# It maps to the GRUB device: (hd0,0) .

...

If I select to boot linux I get the error.

<<rootnoverify (hd0,0)>>
<<chainloader +1>>

<<Error 13: Invalid or unsupported executable format>>

<<Press any key to continue... >>

what is the step i am missing here ?
I have selected linux as a primary partition.

Are you sure that you got the right kernel for your architecture?

What is Rh4u4?

Does sda1 have grub installed? You may need to boot a rescue disc or perhaps solaris, and install grub on sda1 if you want to chainload.

Something along the lines of:

mount /dev/sda1 /mnt
grub-install --root-directory=/mnt /dev/sda1

Was on long leave, late response!!

RG4u4- redhat-4 update 4-2.6 kernel, more precise is below with uname output. This is the output of another system with same architecture and same kernel installed
[root@xxx ~]# uname -a
Linux xxx 2.6.9-42.ELsmp #1 SMP Wed Jul 12 23:32:02 EDT 2006 x86_64 x86_64 x86_64 GNU/Linux

billy, By default my system is booting to solaris, now how can I access sda1 from solaris ?
I had selected 20GB to each of sda1 and sda2 through manual partition during linux installation my first OS.

df -h output from solaris is :
bash-3.00# df -h
Filesystem size used avail capacity Mounted on
/dev/dsk/c0t2d0s0 16G 3.2G 12G 21% /
/devices 0K 0K 0K 0% /devices
ctfs 0K 0K 0K 0% /system/contract
proc 0K 0K 0K 0% /proc
mnttab 0K 0K 0K 0% /etc/mnttab
swap 6.8G 876K 6.8G 1% /etc/svc/volatile
objfs 0K 0K 0K 0% /system/object
/usr/lib/libc/libc_hwcap2.so.1
16G 3.2G 12G 21% /lib/libc.so.1
fd 0K 0K 0K 0% /dev/fd
swap 6.8G 36K 6.8G 1% /tmp
swap 6.8G 28K 6.8G 1% /var/run

I am doing all the installation through network.

The chainload command is executed before the makeactive and you encounter the error before makeactiver is executed.

Try moving makeactive up in the sequence of commands so that it's executed before chainloader.