[syslinux] boot... round 2

Thomas Schmitt scdbackup at gmx.net
Thu Jul 2 05:26:19 PDT 2015


Hi,

> *If* this is really my user case,
> which it really is not - this is the Fedora specificumm,

It could be individually depending on hardware, firmware,
or disk content.

I understand that copy_sysappend_string() is fed by strings
with predefined meanings from sysappend_strings[], as described
in com32/include/syslinux/sysappend.h .
I guess most of them are obtained automatically and not from
the user provided configuration.

The function record() in com32/menu/readconfig.c
picks some of these strings, concatenates them into
ipoptions[4096], and appends this to a thing called
me->cmdline. (struct menu_entry *me;)

So i assume one of the strings

    SYSAPPEND_IP,               /* PXELINUX: ip= address */
    SYSAPPEND_BOOTIF,           /* PXELINUX: BOOTIF= address */
    ...
    SYSAPPEND_FSUUID,           /* Boot filesystem UUID */
    SYSAPPEND_MAX               /* Total number of strings */

contains whitespace which must survive for the boot to
succeed. (List of SYSAPPEND_* indice is in sysappend.h)


(I have to state that i am not a SYSLINUX expert, but
rather the upstream developer of a neighboring project
for producing ISO 9660 filesystems. I believe to understand
the C code within the limited scope given by e.g.
  fgrep -R SYSAPPEND . 
in a SYSLINUX git clone directory.)


Have a nice day :)

Thomas



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