BOCHS and A20

[nitroglycerin]

hi!
how to make bochs emulate disabled A20 line? because if I check if it is enabled (with my bootloader), says it is. and i can use >1024 kb of memory. if the same is done with a real pc, it says, a20 isn't enabled.
so, once again, how to make bochs have the a20 disabled when started?

thanks!

[Pype.Clicker]

well, it's not yet up to BOCHS to do that job, but rather to the bios that bochs is loaded with ...

[slacker]

i dont think bochs automatically enables a20. i think u have to do it.

[Pype.Clicker]

i dont think bochs automatically enables a20. i think u have to do it.

http://www.mega-tokyo.com/forum/index.p ... eadid=1251

according to perica's tests, BOCHS' bios enables A20 gate for you.

[nitroglycerin]

according to perica's tests, BOCHS' bios enables A20 gate for you.

this is just what I'm saying. Bochs enables A20 automatically. And that's my problem. I'd like A20 to be disabled. is that possible?

[Pype.Clicker]

not to my knowledge ... maybe if you get the sources for the BIOS bochs uses, you could find a build option that would let A20 gate disabled ...

[_mark]

If you would like me to test your A20 code under VMWARE I will. I don't know what the initial state of the A20 is offhand though.

_mark()

[Pype.Clicker]

sent via a message

we also have a nice "private messages" system for such off-topic communications

[K.J.]

Yes, Bochs currently enables it by default. If there's enough people wanting it disabled though, I'll have a go at seeing what I can do in the next few weeks to do so.

K.J.

[nitroglycerin]

It is not neccessary to have it disabled, since some people would like it on, and some off.It would be enough just to add a flag in configuration file which would control it: eg. "A20: on" "A20: off"