* David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote: > From: David Woodhouse <dwmw@xxxxxxxxxxxx> > > Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx> > --- > arch/x86/kernel/relocate_kernel_64.S | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S > index 67f6853c7abe..ebbd76c9a3e9 100644 > --- a/arch/x86/kernel/relocate_kernel_64.S > +++ b/arch/x86/kernel/relocate_kernel_64.S > @@ -14,6 +14,8 @@ > #include <asm/nospec-branch.h> > #include <asm/unwind_hints.h> > > +#define DEBUG > + > /* > * Must be relocatable PIC code callable as a C function, in particular > * there must be a plain RET and not jump to return thunk. > @@ -191,6 +193,8 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) > pushw $0xff > lidt (%rsp) > addq $10, %rsp > + > + int3 > #endif /* DEBUG */ That's a really nice piece of debugging code written in assembly, combined with the exception handling feature that generates debug output to begin with. Epic effort. :-) Just curious: did you write this code to debug the series, or was there some original hair-tearing regression that motivated you? Is there's an upstream fix to marvel at and be horrified about in equal measure? I'd argue that this debugging code probably needs a default-off Kconfig option, even with the obvious hard-coded environmental limitations & assumptions it has. Could be useful to very early debugging & would preserve your effort without it bitrotting too obviously. Thanks, Ingo
