On 17.06.2009 19:18, ron minnich wrote: > On Wed, Jun 17, 2009 at 10:15 AM, Marc Jones<[email protected]> wrote: > >> The code is a PCI option ROM that can be copied and run at some >> arbitrary location between 0xC0000 and 0x100000. For 16bit code the >> segment would be loaded and there is no problem. I don't know the >> right way to do this for 32bit flat mode code. >> > > I think we need to seek a common solution, and after discussion with > segher from a while back I think -fpic and -fpie as we do it in v3 are > rather questionable. >
-fpic/-fpie may not be an universally preferred solution, but if GCC developers ever decide to drop support for it, we can still move to LLVM/clang. v3 initram is a bit of a special case because it is PIC calling non-PIC. As far as I can see, GDT trickery would not work for such a case. > What we should look to do is a run command which sets a new entry in > the gdt and does a ljmp which sets CS to that entry. Then we link with > that code to run at 0. This is what FILO does and it works well. > As long as the code does not have to call outside code, using the GDT may indeed be the best option. Regards, Carl-Daniel -- http://www.hailfinger.org/ -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
