On Wed, Mar 18, 2009 at 2:08 PM, Kevin O'Connor kevin@koconnor.net wrote:
The bug is in src/arch/i386/boot/boot.c. The inline assembly in jmp_to_elf_entry uses the "g" flag to pass in parameters. However, "g" allows gcc to use stack relative addressing of parameters. Unfortunately, the inline assembly modifies %esp - and thus the stack relative values become incorrect.
As a guess, without -fomit-frame-pointer, gcc would pass use %ebp relative values and this wouldn't trigger - but regardless it is still a bug.
That's a mighty nice catch. This code has worked unchanged for a long time -- it's amazing how something can just break on you like this.
Thanks
ron