[ipxe-devel] wimboot: loading by grub

[Bernhard Übelacker]

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Hello,
I was just curious why wimboot works when loaded by ipxe, but would
fail when loaded by grub.

I think I found the issue: wimboot expects to be loaded to 0x1000 but
grub loads it to 0x9000.

In more detail in prefix.S at the setup label is a ljmp:
	ljmp	$PREFIX_SEG, $1f
That has PREFIX_SEG hardcoded to segment 0x1000 but we would like to
jump to 0x9000.

Defining PREFIX_SEG to 0x9000 and recompiling produced a version just
working with grub.


With attached patch wimboot can handle to be loaded by both.

Any comments are welcome.

Kind regards,
Bernhard


PS.: Thats an example grub.cfg entry (took me some time to figure out
that we need linux16 and how the on-the-fly packing to cpio archives
is working.



menuentry "wimboot" {
    linux16 /boot/wimboot
    initrd16 \
        newc:bootmgr:/boot/ISO.ROOT/BOOTMGR \
        newc:bcd:/boot/ISO.ROOT/boot/BCD \
        newc:wgl4_boot.ttf:/boot/ISO.ROOT/boot/fonts/wgl4_boot.ttf \
        newc:boot.sdi:/boot/ISO.ROOT/boot/boot.sdi \
        newc:vistape.wim:/boot/ISO.ROOT/vistape.wim
}



The corresponding ipxe script:
#!ipxe
imgfree
kernel /boot/wimboot
initrd /boot/ISO.ROOT/BOOTMGR bootmgr
initrd /boot/ISO.ROOT/boot/BCD bcd
initrd /boot/ISO.ROOT/boot/fonts/wgl4_boot.ttf wgl4_boot.ttf
initrd /boot/ISO.ROOT/boot/boot.sdi boot.sdi
initrd /boot/ISO.ROOT/vistape.wim vistape.wim
imgstat
boot

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