[syslinux] Boot time arguments

H. Peter Anvin hpa at zytor.com
Wed Feb 12 08:30:56 PST 2003


ganapathy murali krishnan wrote:
> Couple of questions:
> 
> Question 1
> --------------
> I am using isolinux to create bootable CDs. I am having the following 
> problems with boot time arguments.
> In my isolinux.cfg I have a section like
> 
> label prep
>      kernel gmklinux
>      append root=/dev/ram0 initrd=rootfs.img image=fdisk mountcd=no \
>                  network=dhcp logfile=/dev/tty4 utils=utils 
> baseurl=http://sysconf/gui
> 

I presume this isn't actually broken up on lines?  SYSLINUX doesn't 
support any form of continuation lines.

> If I type "prep mountcd=yes" at the boot prompt. The boot time arguments 
> I supply does not seem to
> take effect. Once I boot into the kernel, inspection of /proc/1/environ 
> reveals "mountcd=no". I am not using
> any global appends. On the other hand, if I type "gmklinux 
> root=/dev/ram0 ... mountcd=no ... mountcd=yes..."
> on the command line and once I boot into the kernel, /proc/1/environ has 
> both the mountcd options, but
> the second one overrides the first (echo $mountcd returns yes).
> 
> Is this a bug in isolinux?

Hard to say from the info you supply.  Please "cat /proc/cmdline" in 
each case.

> Question 2
> --------------
> This is more of a confirmation of what I understood from the 
> documentation regarding appends
> 
> Suppose an isolinux.cfg file has the following in it
> 
> append GLOBALOPTS
> 
> label opt1
>    kernel k1
>    append LOPT1
> 
> label opt2
>    kernel k2
>    append -
>    append LOPT2
> 
> Then if I type "opt1 ABC", then the actual command line passed to k1 is 
> "GLOBALOPTS LOPT1 ABC"

No; it's "LOPT1 ABC".

> and if I type "opt2 DEF" then the actual command line passed to k2 is 
> "LOPT2 DEF". right?

Yes; the "append -" line is redundant, however.

	-hpa





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