Re: GS register to access thread-specific state on x86
On Wed, May 05, 2004 at 01:39:33PM -0400, Steven Augart wrote:
> Dear debian-glibc list,
>
> It appears that libc6 on the x86 Debian (at least libc6-2.3.2-ds1-11)
> is not compiled to access thread-specific state via the GS register;
> instead, it seems to rely upon masking the low-bits of the stack
> pointer, expecting to find the thread-specific state at the base of
> the stack. This means it gets very upset if a program manipulates the
> stack pointer.
Try using a 2.6 kernel instead. The base glibc supports kernels which
did not allow use of the segment registers in this fashion; if you use
a 2.6 kernel, support for floating stacks (and for NPTL, incidentally)
will automatically be enabled.
Red Hat and SuSE have a tighter coupling between their distribution and
the kernels it supports than Debian does. We still have people using
the 2.2 series kernels.
The decision to not support floating stacks on a 2.4 kernel was made
out of practicality only; we already have three versions of glibc for
x86 systems, and a fourth would be overkill.
--
Daniel Jacobowitz
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