Errors when compiling the kernel

[Roshan George]

Hello,
I was compiling Linux-Libre-3.4-Gnu version using one of the tutorials
I found on a website.
To compile the kernel to meet 64 bit, I issues the command

sudo make $x86_64_defconfig

I get the following errors. I am posting the last few lins of the
above command:-
---
Setup is 16800 bytes (padded to 16896 bytes).
System is 4844 kB
CRC d427dc2e
Kernel: arch/x86/boot/bzImage is ready  (#1)
  Building modules, stage 2.
  MODPOST 3271 modules
ERROR: "__modver_version_show" [drivers/staging/rts5139/rts5139.ko] undefined!
WARNING: modpost: Found 5 section mismatch(es).
To see full details build your kernel with:
'make CONFIG_DEBUG_SECTION_MISMATCH=y'
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2
roshan at roshan-Studio-1558:/usr/src/linux-3.4$
---

Are these errors serious?  If yes, how to rectify it ?