Red Hat Bugzilla – Bug 136700
64-bit PowerPC GDB can't fetch FPSCR
Last modified: 2007-11-30 17:10:52 EST
GDB can't fetch the PowerPC's FPSCR register:
(gdb) print $fpscr
reading register fpscr (#70): Input/output error.
as occures when GDB is doing an inferior function call.
Version-Release number of selected component (if applicable):
ptrace(PTRACE_PEEKUSER, 503, 0x288, 0xffffcdb0) = -1 EIO
and grubbing the headers:
#define PT_FPR0 48
define PT_FPSCR (PT_FPR0 + 32 + 1)
(gdb) print/x (48 + 32 + 1) * 8
$1 = 0x288
suggests that the value is correct.
See bug #91727.
The value of PT_FPSCR for 64-bit userspace is different to the value
for 32-bit. This is because a 'double' is worth two longs for 32-bit
code, and only one for 64-bit code.
I think the kernel is doing the right thing -- if there's a kernel bug
it's purely the evilness of the way the interface is done. If we're
going to start criticising the ptrace interface... :)
Closing NOTABUG. Feel free to argue if you feel strongly ;)
*** This bug has been marked as a duplicate of 91727 ***
Changed to 'CLOSED' state since 'RESOLVED' has been deprecated.