This message means something has invoked an interrupt in the range 0x20
to 0x3f, which it should never have done, since that's in the operating
system range.
Given the complaint about vesamenu further down the page, I'm assuming
the VESA BIOS is invoking a DOS interrupt(!!!!)... although it's very
hard to say for sure.
It might be possible to track down by augmenting syslinux to print the
CS:IP of the supposed DOS system call; if this is the VESA BIOS, it
would be in the range C000:xxxx.
This probably would be a useful hack anyway, so I'll just implement it.
-hpa
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