[syslinux] Can USBstikA boot USBstkB ?!

eas lab lab.eas at gmail.com
Sat Dec 9 23:59:34 PST 2017

Gene Cumm wrote:-
>TC64 still has ISOLINUX.  The basics are to use chain.c32 to boot
>USB-B:p3 but syntax depends.  Ideally, it's a modern enough Syslinux
>version that you can use the "guid" or "label" options to auto-detect
>its location rather than "chain.c32 hdN M".  Hopefully your FS
>label/GUID is unique

 sdb3        Boot        Primary   ext4     [New486Xfce]      7593.79
New486Xfce <- Label per cfdisk
Useing existing working ISOLINUX entry as template:

Since I will assume that the order of mounting / accessing files is:
1: KERNEL /boot/S3P3/vmlinuz-3.2.0-4-486
2: INITRD /boot/S3P3/initrd.img-3.2.0-4-486
3: <mount applicable root> ,
 I'll put the new krnl & initrd, in their own dir in usbA: to avoid
the possible problem of usbB not being readable. from usbA

So minimally modifying a proven entry on usbA:isolinux.cfg gives:-
MENU LABEL video args for S3:P3
Use proven Krn & initrd from S3P3 copied to own /boot/S3P3
KERNEL /boot/S3P3/vmlinuz-3.2.0-4-486
INITRD /boot/S3P3/initrd.img-3.2.0-4-486
APPEND root=LABEL=New486Xfce

==> OK ! usbA Boots the installation on usbBpartition3 !! Thanks.

I previously postponed admitting the full problem, but
usbBpartition3 is problematic, and when booted from GRUB, I need to use:

 linux /boot/vmlinuz-3.2.0-4-486
    root=UUID=3169ee17-bdeb-41fa-984a-94badd02799a ro single

where AFAIK "ro single" gives me recovery-mode and ROOT permission;
where the single VT-mode allows me to set some env. & call `startx`.
I must have root-permission, since this Deb7 crap doesn't know 'sudo'.

The final goal will be using "video=vesa:ywrap,mtrr vga=788"
 in isolinux; since these parameters are the only known way to get
 the important app to use proper <font sizes>.

When the good fonts show [only acheivable by booting DVD-rescue]
  `cat /proc/cmdline` shows:---
'video=vesa:ywrap,mtrr vga=788 initrd=/install.386/gtk/initrd.gz
   rescue/enable=true -- quiet

indicating that "video=vesa:ywrap,mtrr vga=788" is needed by isolinux
to get the essential good font.
So I first needed to confirm that usbA, which has a proven isolinux
could boot usbBpartition3, which has the special app, that needs
"video=vesa:ywrap,mtrr vga=788" via isolinux.
Searching the DVD, for how/where "video=vesa:ywrap,mtrr vga=788"
is used by isolinux to launch the <graphics rescue mode> shows eg:-
label expertgui
  menu label Graphical expert install
  kernel /install.386/vmlinuz
  append desktop=xfce priority=low video=vesa:ywrap,mtrr vga=788
/initrd.gz --
So I'll try to use:--

KERNEL /boot/S3P3/vmlinuz-3.2.0-4-486
INITRD /boot/S3P3/initrd.img-3.2.0-4-486
APPEND root=LABEL=New486Xfce video=vesa:ywrap,mtrr vga=788
which is a DISASTER: failure by isolinux with NO indication WHY,
is worse that programming a uProc in hex via a TTY in the 70s!

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