Re: RFC: partially available registers

Tom Tromey
2011-07-22T18:56:04Z

>>>>> "Pedro" == Pedro Alves <pedro@codesourcery.com> writes:

Pedro> Ah, that's it then. I was curious to know why were the
Pedro> upper parts of the ymm unavailable.

amd64_linux_fetch_inferior_registers calls ptrace(PTRACE_GETREGSET)
to fetch the registers. Then it passes this to amd64_supply_xsave,
which calls i387_supply_xsave. This function then decodes the "XCR0"
flag and determines that the upper parts were not supplied by the
kernel; that is, we take the true branch here:

if ((clear_bv & I386_XSTATE_AVX))
p = NULL;
else
p = regs;

Tom