Bert Freudenberg schrieb:
On Oct 5, 2007, at 5:05 , Keith Hodges wrote:
Indeed you make a good point, if we can pick a good number that runtimes can use without traversing the image then great. What number should it be?
I don't think any OS (except for DOS maybe) would guarantee you a specific start address.
It does not need to guarantee a start address but just pick the same one most of the time (for example, as long as the VM binary stays the same). I think Squeak already does this. See below for another option.
Since OLPC applications have a virtual linux box to themselves can we just pick a number that suits us/them?
I wouldn't think so ... but it is an interesting idea. I will ask the OLPC guys.
It's not difficult for a VM to use mmap() on /dev/null (or was it /dev/zero?) to allocate memory for the image to any given address under linux (as long as the CPU/OS version supports memory at that address). If a VM did this, it could have a fixed image start address even across VM versions. Even cooler would be to mmap() the image file directly with copy-on-write behavior for almost instantaneous startup.
Cheers, Hans-Martin