Re: [PATCH][TAKE 4] THE LINUX/I386 BOOT PROTOCOL - Breaking the 256 limit

[John Coffman]

At 11:17 AM  Friday 5/5/2006, you wrote:
> John Coffman wrote:
> The problem isn't that LILO can't handle more than some number of 
> characters; that's a LILO issue and doesn't affect the kernel.
>
> The problem is that some people have reported that the kernel 
> crashes if booted with LILO and the size limit is more than 
> 255.  They haven't so far commented on how they observed that, and 
> that's a major problem.

Just re-compiling LILO with the  COMMAND_LINE_SIZE  parameter changed 
from 256 to 512 will not work.  A .bss area must be moved to avoid 
clobbering the kernel header.


> If the issue is that LILO doesn't null-terminate overlong command 
> lines, then that's pretty easy to deal with:
>
> - If the kernel sees protocol version <= 2.01, limit is 255+null.
> - If the kernel sees protocol version >= 2.02, but ID is 0x1X, limit 
> is 255+null.
> - Otherwise limit is higher.
>
> When LILO is fixed, it has to bump the ID byte version number.
>
> What ID byte values has LILO used?

For the last 8 years LILO has used 0x02 as the loader ID.

If anyone wishes to test a version of LILO that is able to pass a 512 
byte command line, then the "22.7.2-beta8" version in the "beta" 
directory should be tried.  It moves the offending ".bss" area to 
avoid the header clobber.  However, I have not yet changed the loader ID.

--John



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