I am trying to debug spi-xilinx.c using kgdb. The symbols for spi-xilinx.c are not in vmlinux.

I'm looking for symbols as follows:
$nm vmlinux | grep xilinx
$

I included CONFIG_SPI_XILINX in my kernel and built it per these instructions:
https://wiki.centos.org/HowTos/Custom_Kernel

Note that I am using RHEL 7 but the centos instructions worked well for me.

I verified that the module was in fact included in the kernel as follows:

$ grep xilinx /proc/kallsyms
ffffffff81487220 t xilinx_spi_setup
ffffffff81487230 t xilinx_spi_irq
ffffffff814872d0 t xilinx_spi_txrx_bufs
ffffffff814874b0 t xilinx_spi_setup_transfer
ffffffff81487520 t xilinx_spi_chipselect
ffffffff81487610 T xilinx_spi_deinit
ffffffff81487680 t xilinx_spi_remove
ffffffff814876b0 T xilinx_spi_init
ffffffff81487a60 t xilinx_spi_probe
ffffffff8174f3c0 r xilinx_spi_of_match
ffffffff819b5330 r __ksymtab_xilinx_spi_deinit
ffffffff819b5340 r __ksymtab_xilinx_spi_init
ffffffff819c9fc8 r __kcrctab_xilinx_spi_deinit
ffffffff819c9fd0 r __kcrctab_xilinx_spi_init
ffffffff819e8968 r __kstrtab_xilinx_spi_deinit
ffffffff819e897a r __kstrtab_xilinx_spi_init
ffffffff81addf80 d xilinx_spi_driver
ffffffff81babf1f t xilinx_spi_driver_init
ffffffff81cdb170 t __initcall_xilinx_spi_driver_init6
ffffffff81cffdf3 t xilinx_spi_driver_exit

I selected kernel config options as indicated in kernel doc for kgdb:

# CONFIG_DEBUG_RODATA is not set

CONFIG_FRAME_POINTER=y

CONFIG_KGDB=y

CONFIG_KGDB_SERIAL_CONSOLE=y

I need the xilinx symbols in vmlinux so I can do source code level debug of spi-xilinx.c. What am I missing here? How do I get vmlinux to include spi-xilinx.c symbols?

Thank you for taking the time to help.

How did you configure the xilinx driver in your kernel? The CONFIG_ option should be saying =y and not =m. Please check this.

Yes:

CONFIG_SPI_XILINX=y

I decided to try building spi-xilinx.c as a module:

CONFIG_SPI_XILINX=m

The resulting loadable modules generated during the kernel build did not have debug info either. However, I was able to build spi-xilinx.c outside the kernel source tree with this makefile which includes the -g option:

obj-m := spi-xilinx.o
MY_CFLAGS += -g -DDEBUG
ccflags-y += ${MY_CFLAGS}
CC += ${MY_CFLAGS}

KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
MODULES=$(obj-m:.o=.ko)
XZ_MODULES=$(MODULES:.ko=.ko.xz)

all:
$(MAKE) -C $(KERNELDIR) M=$(PWD)

The resulting loadable module includes debug info. And I can also debug by adding printk statements.

I would still like to know why vmlinux does not contain debug info for components I included as "built-in", i.e.,

CONFIG_SPI_XILINX=y

In the 'kernel hacking' section of the config, select 'compile kernel with debug info'.