Re: [patch] tls-2.5.31-C3

Ingo Molnar
2002-08-12T08:47:46Z

On 12 Aug 2002, Alan Cox wrote:

> > No. The problem is that there are some BIOS's that contain code that (even
> > though they are called in protected mode) load 0x40 into ds and expect to
> > be able to reference stuff ... Causes really interesting OOPSs :-(
>
> Which does mean you can steal the old TLS value and put it back across
> the calls just by changing the TLS data for that process. For that
> matter on Windows emulation I thought Windows also needed 0x40 to be the
> same offset as the BIOS does so can't we leave it hardwired ?

i have no problem with hardwiring it (and excluding it from the TLS
allocation/setting syscalls) - in fact i almost did it that way. The
question is, is the required descriptor format 100% the same for all APM
variants, Wine and Windows and DOS emulators? It would suck if we had a
bad descriptor and also removed the ability of Wine to trap 0x40 access.

but, couldnt APM use its own private GDT for real-mode calls, with 0x40
filled in properly? That would pretty much decouple things.

Ingo