[Xen-users] Re: Xen and TLS, -mno-tls-direct-seg-refs needed?

["Molle Bestefich" <molle.bestefich@xxxxxxxxx>]

Sven Köhler wrote:
> If i have a multilib x86_64 system (that means: 64-bit glibc and
> 32-bit glibc are present), then the 32-bit does still needs this
> -mno-tls-direct-seg-refs neede - or does it not?
I honestly have NO idea.

I would imagine that it works like this:

Since the CPU is running in 64-bit mode by virtue of you running a
64-bit OS, any 32-bit code is executed in a fashion where the
operating system has first told the CPU to set up a virtual 4GB 32-bit
environment.  Any kernel calls from 32-bit code goes into a
translation layer the kernel has, and the translation layer knows how
to switch the CPU to 64-bit mode to actually perform the kernel call
onto the 64-bit kernel.  Xen would live entirely outside of the 4 GB
virtual 32-bit area, being used only from the 64-bit kernel, and being
protected by whatever mechanism it is that Xen normally uses on
x86_64.

But I'm just imagining these things, I haven't actually read a thing
about CPUs since the switch from 80286 to 80386.  Hope someone who
actually knows comes along :-).

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users