iris, and darwin tweaks

[bsittler]

i think iris might be starting to talk. the words are few, and the pronunciation odd enough that i'm never really sure, but i think i've been hearing "fish", "kitty", "guido" (one of the cats), and "no" used in more-or-less appropriate situations. rebbyribs is a bit more skeptical, but i'm sure iris will talk clearly and distinctly soon enough.

note: what

Comments

[two_pi_r]

dd of=/dev/kmem bs=1 seek=$(( 0x$(nm /mach_kernel | fgrep _iso_font | awk '{print $1}') + 128 * 16 ))

Yow. How many kernel panics did you have to go through when figuring this out?!

[bsittler]

zero. the font is a publicly exported symbol (_iso_font) with known contents (256 8x16-bit bitmaps), the font layout is well known (ISO 8859-1 with VT100 alternate character set [blank in the distributed kernel] in the C1 range [corresponding to characters 0x80-0x9f]), the script is carefully modifying only the correct region of the font, and it has a precondition check to make sure the previous data was the expected blank cells

[two_pi_r]

touch&eeacute;. I just see "dd of=/dev/kmem" and think "panic city". Of course, the only thing I've done with dd of=/dev/kmem is with an if=/dev/urandom just to see what happens, so hey.

[bsittler]

yeah, that sounds fun. how well did it stand up to the fuzzing?

[two_pi_r]

Not very. The screen barfed colors and blinks, and of course the machine locked.

[bsittler]

yeah, most software (kernels included) is not written with "major random memory corruption" as a design constraint. i guess interplanetary probes and some satellites are exceptions here.

[bsittler]

that said, i did go ahead and add a warning and disclaimer. Bad Things Might Happen, but you run this stuff entirely at your own risk and if your computer turns into a smoking brick that's your problem, not mine ☺.

[bsittler]

also the earlier project of examining the darwin/mac os x console font in c (which is a read-only operation) made me fairly confident about what was where.

[two_pi_r]

Also touch&eeacute;