On Tue, Jul 07, 2020 at 05:59:25PM -0400, Arvind Sankar wrote: > On Mon, Jul 06, 2020 at 08:45:58PM -0700, Nick Terrell wrote: > > From: Nick Terrell <terrelln@xxxxxx> > > > > Don't export symbols if XXH_PREBOOT is defined. > > > > This change is necessary to get xxhash to work in a preboot environment, > > which is needed to support zstd-compressed kernels. > > The usual way to do it is by adding -D__DISABLE_EXPORTS to the CFLAGS, which will > cause EXPORT_SYMBOL to be stubbed out. Doesn't that work here? This is quite rare, actually: $ git grep DISABLE_EXPORTS arch/s390/purgatory/Makefile:CFLAGS_sha256.o := -D__DISABLE_EXPORTS arch/x86/boot/compressed/kaslr.c:#define __DISABLE_EXPORTS arch/x86/purgatory/Makefile:CFLAGS_sha256.o := -D__DISABLE_EXPORTS drivers/firmware/efi/libstub/Makefile: -D__DISABLE_EXPORTS include/linux/export.h:#if !defined(CONFIG_MODULES) || defined(__DISABLE_EXPORTS) But yes, it seems that would be the better approach. -- Kees Cook
