Re: [PATCH] Mask x86 segment registers in Windows gdbserver

[Tom Tromey <tromey@adacore.com>]

>> A test internal to AdaCore prints the segment registers.  When run
>> using gdbserver, it shows:
>> (gdb) print /x $gs
>> $6 = 0x2b0000
>> However, the segment registers are only 16 bits -- so this has some
>> invalid bits.
>> gdb's windows-nat.c has long had a fix for this problem.  This patch
>> applies the fix to gdbserver as well.

John> LGTM.  Treating the x86 seg regs as 32-bits has required workarounds in
John> various places, but not easily fixable unfortunately.

Well, to my surprise, this patch caused regressions in our internal
tester.

It works again if I explicitly exclude the 'ss' register, like:

  if (!windows_process.wow64_process)
    return r >= AMD64_CS_REGNUM && r <= AMD64_GS_REGNUM && r != 19;

Now, this seems "ok" to do in some sense.  However, I can't explain why
native gdb works fine, as it has the same logic in
amd64_windows_segment_register_p.

I'd welcome any thoughts you (or anybody) might have.

Tom