> The GDB behavior looks to be different between the two cases -- with vs > without gdb server, when I checked the GS/GSBASE values on the ptrace front.
64-bit GDB doesn't support FSGSBASE for 32-bit inferiors and it looks like gdbserver might not support FSGSBASE, at all. I had added support for the former as part of the tests I wrote about a year ago [1] but never submitted the patch. Was the discussion ever concluded? The general behavior should be that GDB reads a regset, overwrites the registers it knows about, and writes it back again to preserve the original values of registers it doesn't know about. When I log the values that are read and written for FSGSBASE, however, it looks like ptrace is returning a non-zero GS_BASE on a read and gdbserver is writing zero on the next write. Chang, is that also what you were seeing? Regards, Markus. [1] https://lkml.org/lkml/2019/11/29/306 Intel Deutschland GmbH Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany Tel: +49 89 99 8853-0, www.intel.de Managing Directors: Christin Eisenschmid, Gary Kershaw Chairperson of the Supervisory Board: Nicole Lau Registered Office: Munich Commercial Register: Amtsgericht Muenchen HRB 186928
