> On Apr 11, 2019, at 6:41 AM, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: > > On Wed, Apr 10, 2019 at 02:13:34PM -0700, Nadav Amit wrote: >> Untested, but clearly bit 12 is the one that needs to be tested. >> >> Signed-off-by: Nadav Amit <nadav.amit@xxxxxxxxx> >> --- >> x86/cstart64.S | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/x86/cstart64.S b/x86/cstart64.S >> index 21db10f..8626f02 100644 >> --- a/x86/cstart64.S >> +++ b/x86/cstart64.S >> @@ -243,7 +243,7 @@ start64: >> setup_5level_page_table: >> /* Check if 5-level paging has already enabled */ >> mov %cr4, %rax >> - test $12, %eax >> + bt $12, %eax >> jnz lvl5 > > Unfortunately BT doesn't affect RFLAGS.ZF, so 'jnz' needs to be changed > to 'jc'. Or alternatively, do 'test $1000, %eax'. Of course. Stupid me, but it’s not worse than it was before ;-) I’ll send a revised version. Thanks.
