Building the coreboot 4.7 from source is now causing an error,
ch341a_spi.c: In function 'ch341a_spi_init':
ch341a_spi.c:447:2: error: 'libusb_set_debug' is deprecated: Use libusb_set_option instead [-Werror=deprecated-declarations]
libusb_set_debug(NULL, 3); // Enable information, warning and error messages (only).
^~~~~~~~~~~~~~~~
In file included from ch341a_spi.c:25:0:
/usr/include/libusb-1.0/libusb.h:1300:18: note: declared here
void LIBUSB_CALL libusb_set_debug(libusb_context *ctx, int level);
^~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Makefile:1043: recipe for target 'ch341a_spi.o' failed
make: *** [ch341a_spi.o] Error 1the libusb-1.0-0 v1.0.22 was a recent core update, but the patch to the kernel was added on the 27th April 2018 which is yet to make its way into PureOS, so until then one cannot upgrade CoreBoot.