Hi, 2007/6/29, Paul Brook <[EMAIL PROTECTED]>:
I'd expect the overhead of SIGSEGV+mmap to be prohibitive. I don't have numbers to back this up, but experience with MIPS system emulation shows that TLB miss cost can have significant effect on overall performance.
I'd say this can't be worse than on MacOS X where Mach exception handling is terribly slow. Typically 100 usec per fault caught+mprotect where Linux requires less than 5 usec to do the same.
Like Fabrice, I think this would be most useful in combination with some sort of hypervisor. Somewhere on my TODO list is porting qemu to run directly as a paravirtual Xen DomU. This means you can insert the guest pagetable walk directly into the host mmu fault handler, and do clever things with shadow pagetables.
This would be great. As Fabrice mentioned, the tricky part would be to run the translator in the upper part or lower part of the 32-bit address space. Would fixing compilation with -pie help this (with some provisions for the dyngen ops) or do you see another means to achieve this? -- Gwenolé.
