Re: THE LINUX/I386 BOOT PROTOCOL - Breaking the 256 limit

From: Coywolf Qi Hunt
Date: Mon Oct 10 2005 - 20:51:20 EST

On 9/7/05, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> Alon Bar-Lev wrote:
> >
> > Hello Peter, I've written a reply before but got no response...
> >
> > The idea of putting arguments in initramfs is not practical, since the
> > whole idea is to have the same image of system and affecting its
> > behavior using the boot loader...
> >
> No, you're wrong. The boot loader can synthesize an initramfs.
> > I would like to push forward the idea to extend the command-line size...
> >
> > All we need for start is an updated version of the "THE LINUX/I386 BOOT
> > PROTOCOL" document that states that in the 2.02+ protocol the boot
> > loader should set cmd_line_ptr to a pointer to a null terminated string
> > without any size restriction, specifying that the kernel will read as
> > much as it can.
> Already pushed to Andrew. I will follow it up with a patch to extend
> the command line, at least to 512.
> > After I get this update, I will try to work with GRUB and LILO so that
> > they will fix their implementation. Currently they claim that they
> > understand that they should truncate the string to 256.
> >
> > After that I will provide my simple patch for setting the maximum size
> > the kernel allocates in the configuration.
> >
> > BTW: Do you know why the COMMAND_LINE_SIZE constant is located in two
> > separate include files?
> No, I don't. It could be because one is included from assembly code in
> the i386 architecture.

The kernel uses the setup.h COMMAND_LINE_SIZE for both assembly and C
code. COMMAND_LINE_SIZE in param.h is only for bootloader IMHO.
Coywolf Qi Hunt
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