Hi!
Am 20.07.2010 11:31, schrieb Michael Schnell:
On 07/19/2010 08:33 PM, Hans-Peter Diettrich wrote:
Windows uses segment registers in exception handling, i.e. it should
be possible. But the segment descriptor/selector must point to the
correct thread-memory address in the address space, what can not be
achieved in application code.
If Windows sets the segment registers and the application is not
supposed to modify them (and assume them to be restored after
preemption), maybe one of them is a pointer to some thread-dedicated
memory area, that by can be used (or is used by the OS) to hold a
pointer to the threadvars or to hold the threadvars themselves (if the
size of the threadvar area is denoted in the exe file and thus known to
the OS, which might kindly allocate it when a thread is created).
According to
http://en.wikipedia.org/wiki/Thread-local_storage#Windows_implementation
you use a dedicated API to modify the TLS. And according to
http://en.wikipedia.org/wiki/Thread_Environment_Block the address of the
TLS is indeed accessible/saved in the segment registers.
Regards,
Sven
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