Bug#717557: gcc-4.8: can't compile working 64bit kernel with 32bit userspace gcc-4.8

[Zlatko Calusic <zcalusic@bitsync.net>]

Package: gcc-4.8
Version: 4.8.1-7
Severity: normal

Somewhere after 4.8.1-2 (I believe that version worked OK) I lost the
ability to compile a working 64bit kernel on a 32bit userspace
machine. This report is sent from a full 64bit machine, but it
pertains only to the 32bit version of gcc-4.8 (same version)!

By working 64bit kernel I mean the kernel that can be successfully
booted. The compilation phase actually finishes, but it is flooded
with warnings like these:

include/net/sock.h: In function ‘skb_add_data_nocache’:
include/net/sock.h:1831:12: warning: pointer targets in passing argument 4 of ‘skb_do_copy_data_nocache’ differ in signedness [-Wpointer-sign]
            copy, offset);
            ^
include/net/sock.h:1805:19: note: expected ‘char *’ but argument is of type ‘unsigned char *’
 static inline int skb_do_copy_data_nocache(struct sock *sk, struct sk_buff *skb,
                   ^

include/linux/syscalls.h:536:17: note: expected ‘char *’ but argument is of type ‘unsigned char *’
 asmlinkage long sys_read(unsigned int fd, char __user *buf, size_t count);
                 ^
init/do_mounts_rd.c:134:2: warning: pointer targets in passing argument 2 of ‘sys_read’ differ in signedness [-Wpointer-sign]
  sys_read(fd, buf, size);
  ^

The resulting kernel crashes shortly after boot.

-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.11.0-rc1+ (SMP w/4 CPU cores; PREEMPT)
Locale: LANG=C, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages gcc-4.8 depends on:
ii  binutils        2.23.52.20130620-1
ii  cpp-4.8         4.8.1-7
ii  gcc-4.8-base    4.8.1-7
ii  libc6           2.17-7
ii  libcloog-isl4   0.18.0-2
ii  libgcc-4.8-dev  4.8.1-7
ii  libgmp10        2:5.1.2+dfsg-2
ii  libisl10        0.11.2-1
ii  libmpc3         1.0.1-1
ii  libmpfr4        3.1.1-1
ii  zlib1g          1:1.2.8.dfsg-1

Versions of packages gcc-4.8 recommends:
ii  libc6-dev  2.17-7

Versions of packages gcc-4.8 suggests:
pn  binutils-gold        <none>
ii  gcc-4.8-doc          4.8.1-1
pn  gcc-4.8-locales      <none>
pn  gcc-4.8-multilib     <none>
pn  libasan0-dbg         <none>
pn  libatomic1-dbg       <none>
pn  libbacktrace1-dbg    <none>
pn  libgcc1-dbg          <none>
pn  libgomp1-dbg         <none>
pn  libitm1-dbg          <none>
pn  libmudflap0-4.8-dev  <none>
pn  libmudflap0-dbg      <none>
pn  libquadmath0-dbg     <none>
pn  libtsan0-dbg         <none>

-- no debconf information