Kconfig和Makefile
在linux-2.6.31/drivers/char目录下建立子目录：
bhsong@bhsong-laptop:~/develop/svn/ldd6410/linux-2.6.31/drivers/char$ mkdir driver_examples
将三个驱动hello.c、globalmem.c、globalfifo.c拷入driver_examples目录：
cd driver_examples/
cp ../../../../training/kernel/drivers/hello/hello.c ./
cp ../../../../training/kernel/drivers/globalmem/globalmem.c ./
cp ../../../../training/kernel/drivers/globalmem/globalfifo.c ./
修改drivers/char下面的Kconfig和Makefile导入driver_examples目录：
·在drivers/char/Kconfig中添加：
source "drivers/char/driver_examples/Kconfig"
·添加drivers/char/driver_examples/Kconfig文件：
#
# driver examples configuration
#
menuconfig DRIVER_EXAMPLE
tristate "driver examples in 'Explain Linux Device Drivers in detail'"
---help---
say Yes to build-in hello world, globalmem, globalfifo, say M to get
those kernel modules
if DRIVER_EXAMPLE
config HELLO_WORLD
tristate "Hello World"
---help---
To compile this driver as a module, choose M here; the module will be
called hello.mem
config GLOBALMEM
tristate "globalmem"
---help---
To compile this driver as a module, choose M here; the module will be
called globalmem.
config GLOBALFIFO
tristate "globalfifo"
---help---
To compile this driver as a module, choose M here; the module will be
called globalfifo.
endif # DRIVER_EXAMPLE
这将形成如下菜单：
driver examples in 'Explain Linux Device Drivers in detail' ────────────
│ Arrow keys navigate the menu. selects submenus --->. Highlighted
│ letters are hotkeys. Pressing includes, excludes, modularizes
│ features. Press to exit, for Help, for Search. Legend:
│ [*] built-in [ ] excluded module < > module capable
│
│ ┌────────────────────────────────────── │
│ │ --- driver examples in 'Explain Linux Device Drivers in detail' │ │
│ │ < > Hello World (NEW) │ │
│ │ < > globalmem (NEW) │ │
│ │ < > globalfifo (NEW) │ │
│ │ │ │
·在drivers/char/Makefile中添加：
obj-$(CONFIG_DRIVER_EXAMPLE) += driver_examples/
·添加drivers/char/driver_examples/Makefile文件：
obj-$(CONFIG_HELLO_WORLD) += hello.o
obj-$(CONFIG_GLOBALMEM) += globalmem.o
obj-$(CONFIG_GLOBALFIFO) += globalfifo.o
相关的Kconfig和Makefile patch如下：
Index: drivers/char/Kconfig
===================================================================
--- drivers/char/Kconfig (revision 87)
+++ drivers/char/Kconfig (working copy)Index: drivers/char/driver_examples/Makefile
===================================================================
--- drivers/char/driver_examples/Makefile (revision 0)
+++ drivers/char/driver_examples/Makefile (revision 0)
@@ -0,0 +1,3 @@
+obj-$(CONFIG_HELLO_WORLD) += hello.o
+obj-$(CONFIG_GLOBALMEM) += globalmem.o
+obj-$(CONFIG_GLOBALFIFO) += globalfifo.o
@@ -1110,5 +1110,7 @@
source "drivers/s390/char/Kconfig"
+source "drivers/char/driver_examples/Kconfig"
+
endmenu
Index: drivers/char/Makefile
===================================================================
--- drivers/char/Makefile (revision 87)
+++ drivers/char/Makefile (working copy)
@@ -111,6 +111,8 @@
obj-$(CONFIG_JS_RTC) += js-rtc.o
js-rtc-y = rtc.o
+obj-$(CONFIG_DRIVER_EXAMPLE) += driver_examples/
+
# Files generated that shall be removed upon make clean
clean-files := consolemap_deftbl.c defkeymap.c
Index: drivers/char/driver_examples/Kconfig
===================================================================
--- drivers/char/driver_examples/Kconfig (revision 0)
+++ drivers/char/driver_examples/Kconfig (revision 0)
@@ -0,0 +1,31 @@
+#
+# driver examples configuration
+#
+
+menuconfig DRIVER_EXAMPLE
+ tristate "driver examples in 'Explain Linux Device Drivers in detail'"
+ ---help---
+ say Yes to build-in hello world, globalmem, globalfifo, say M to get
+ those kernel modules
+
+if DRIVER_EXAMPLE
+
+config HELLO_WORLD
+ tristate "Hello World"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called hello.
+
+config GLOBALMEM
+ tristate "globalmem"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called globalmem.
+
+config GLOBALFIFO
+ tristate "globalfifo"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called globalfifo.
+
+endif # DRIVER_EXAMPLE
+Index: drivers/char/Kconfig
===================================================================
--- drivers/char/Kconfig (revision 87)
+++ drivers/char/Kconfig (working copy)
@@ -1110,5 +1110,7 @@
source "drivers/s390/char/Kconfig"
+source "drivers/char/driver_examples/Kconfig"
+
endmenu
Index: drivers/char/Makefile
===================================================================
--- drivers/char/Makefile (revision 87)
+++ drivers/char/Makefile (working copy)
@@ -111,6 +111,8 @@
obj-$(CONFIG_JS_RTC) += js-rtc.o
js-rtc-y = rtc.o
+obj-$(CONFIG_DRIVER_EXAMPLE) += driver_examples/
+
# Files generated that shall be removed upon make clean
clean-files := consolemap_deftbl.c defkeymap.c
Index: drivers/char/driver_examples/Kconfig
===================================================================
--- drivers/char/driver_examples/Kconfig (revision 0)
+++ drivers/char/driver_examples/Kconfig (revision 0)
@@ -0,0 +1,31 @@
+#
+# driver examples configuration
+#
+
+menuconfig DRIVER_EXAMPLE
+ tristate "driver examples in 'Explain Linux Device Drivers in detail'"
+ ---help---
+ say Yes to build-in hello world, globalmem, globalfifo, say M to get
+ those kernel modules
+
+if DRIVER_EXAMPLE
+
+config HELLO_WORLD
+ tristate "Hello World"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called hello.
+
+config GLOBALMEM
+ tristate "globalmem"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called globalmem.
+
+config GLOBALFIFO
+ tristate "globalfifo"
+ ---help---
+ To compile this driver as a module, choose M here; the module will be
+ called globalfifo.
+
+endif # DRIVER_EXAMPLE
Index: drivers/char/driver_examples/Makefile
===================================================================
--- drivers/char/driver_examples/Makefile (revision 0)
+++ drivers/char/driver_examples/Makefile (revision 0)
@@ -0,0 +1,3 @@
+obj-$(CONFIG_HELLO_WORLD) += hello.o
+obj-$(CONFIG_GLOBALMEM) += globalmem.o
+obj-$(CONFIG_GLOBALFIFO) += globalfifo.o
选中三个模块：
driver examples in 'Explain Linux Device Drivers in detail' ────────────
│ Arrow keys navigate the menu. selects submenus --->. Highlighted
│ letters are hotkeys. Pressing includes, excludes, modularizes
│ features. Press to exit, for Help, for Search. Legend:
│ [*] built-in [ ] excluded module < > module capable
│
│ ┌────────────────────────────────────── │
│ │ --- driver examples in 'Explain Linux Device Drivers in detail' │ │
│ │ Hello World │ │
│ │ globalmem │ │
│ │ globalfifo │ │
│ │ │ │
在linux-2.6.31下运行：
bhsong@bhsong-laptop:~/develop/svn/ldd6410/linux-2.6.31$ make modules
以loopback方式mount根文件系统，譬如对于skyeye的initrd.img运行如下命令：
...skyeye/training-simulation$ sudo mount -o loop initrd.img initrd
将所有模块安装到根文件系统：
make INSTALL_MOD_PATH=/home/bhsong/develop/training/skyeye/training-simulation/initrd modules_install
请根据你的路径，正确的设置INSTALL_MOD_PATH。安装之后，所有模块以及模块间依赖关系进入根文件系统：
initrd/lib/modules$ tree
.
`-- 2.6.31.6-svn79
|-- build -> /home/bhsong/develop/svn/ldd6410/linux-2.6.31
|-- kernel
| |-- drivers
| | |-- cdrom
| | | `-- cdrom.ko
| | |-- char
| | | `-- driver_examples
| | | |-- globalfifo.ko
| | | |-- globalmem.ko
| | | `-- hello.ko
| | |-- input
| | | `-- gameport
| | | `-- gameport.ko
| | `-- scsi
| | |-- ch.ko
| | |-- scsi_wait_scan.ko
| | |-- sr_mod.ko
| | `-- st.ko
| |-- lib
| | |-- ts_bm.ko
| | |-- ts_fsm.ko
| | `-- ts_kmp.ko
| `-- net
| |-- ipv4
| | |-- netfilter
| | | |-- arp_tables.ko
| | | |-- arpt_mangle.ko
| | | |-- arptable_filter.ko
| | | |-- ip_queue.ko
| | | |-- ip_tables.ko
| | | |-- ipt_ECN.ko
| | | |-- ipt_LOG.ko
| | | |-- ipt_MASQUERADE.ko
| | | |-- ipt_NETMAP.ko
| | | |-- ipt_REDIRECT.ko
| | | |-- ipt_REJECT.ko
| | | |-- ipt_ULOG.ko
| | | |-- ipt_addrtype.ko
| | | |-- ipt_ah.ko
| | | |-- ipt_ecn.ko
| | | |-- iptable_filter.ko
| | | |-- iptable_mangle.ko
| | | |-- iptable_nat.ko
| | | |-- iptable_raw.ko
| | | |-- nf_conntrack_ipv4.ko
| | | |-- nf_defrag_ipv4.ko
| | | |-- nf_nat.ko
| | | |-- nf_nat_amanda.ko
| | | |-- nf_nat_ftp.ko
| | | |-- nf_nat_h323.ko
| | | |-- nf_nat_irc.ko
| | | |-- nf_nat_pptp.ko
| | | |-- nf_nat_proto_gre.ko
| | | |-- nf_nat_proto_udplite.ko
| | | |-- nf_nat_sip.ko
| | | |-- nf_nat_snmp_basic.ko
| | | `-- nf_nat_tftp.ko
| | |-- tcp_bic.ko
| | |-- tcp_htcp.ko
| | `-- tcp_westwood.ko
| `-- netfilter
| |-- ipvs
| | `-- ip_vs.ko
| |-- nf_conntrack.ko
| |-- nf_conntrack_amanda.ko
| |-- nf_conntrack_ftp.ko
| |-- nf_conntrack_h323.ko
| |-- nf_conntrack_irc.ko
| |-- nf_conntrack_netbios_ns.ko
| |-- nf_conntrack_netlink.ko
| |-- nf_conntrack_pptp.ko
| |-- nf_conntrack_proto_gre.ko
| |-- nf_conntrack_proto_udplite.ko
| |-- nf_conntrack_sip.ko
| |-- nf_conntrack_tftp.ko
| |-- nfnetlink.ko
| |-- nfnetlink_log.ko
| |-- nfnetlink_queue.ko
| |-- x_tables.ko
| |-- xt_CLASSIFY.ko
| |-- xt_CONNMARK.ko
| |-- xt_HL.ko
| |-- xt_MARK.ko
| |-- xt_NFLOG.ko
| |-- xt_NFQUEUE.ko
| |-- xt_RATEEST.ko
| |-- xt_TCPMSS.ko
| |-- xt_cluster.ko
| |-- xt_comment.ko
| |-- xt_connbytes.ko
| |-- xt_connlimit.ko
| |-- xt_connmark.ko
| |-- xt_conntrack.ko
| |-- xt_dccp.ko
| |-- xt_dscp.ko
| |-- xt_esp.ko
| |-- xt_hashlimit.ko
| |-- xt_helper.ko
| |-- xt_hl.ko
| |-- xt_iprange.ko
| |-- xt_length.ko
| |-- xt_limit.ko
| |-- xt_mac.ko
| |-- xt_mark.ko
| |-- xt_multiport.ko
| |-- xt_owner.ko
| |-- xt_pkttype.ko
| |-- xt_policy.ko
| |-- xt_quota.ko
| |-- xt_rateest.ko
| |-- xt_realm.ko
| |-- xt_recent.ko
| |-- xt_state.ko
| |-- xt_statistic.ko
| |-- xt_string.ko
| |-- xt_tcpmss.ko
| |-- xt_tcpudp.ko
| |-- xt_time.ko
| `-- xt_u32.ko
|-- modules.alias
|-- modules.ccwmap
|-- modules.dep
|-- modules.ieee1394map
|-- modules.inputmap
|-- modules.isapnpmap
|-- modules.ofmap
|-- modules.order
|-- modules.pcimap
|-- modules.seriomap
|-- modules.symbols
|-- modules.usbmap
`-- source -> /home/bhsong/develop/svn/ldd6410/linux-2.6.31
17 directories, 116 files
启动Linux，对于skyeye为：
sudo skyeye -e vmlinux -c skyeye-standalone.conf
...
Welcome to
_ _____ __ __ _ _
/ \ / __ \ / \_/ \ | | |_|
/ _ \ | | | | / /\ /\ \ | | _ ____ _ _ _ _
/ /_\ \ | |__| | / / \_/ \ \| | | | _ \| | | |\ \/ /
/ /___\ \ | |__\ \ | | | || |___ | | |_| | |_| |/ \
/_/ \_\| | \_\|_| |_||_____||_|_| |_|\____|\_/\_/
ARMLinux for Lihacker LDD6410
For further information please check:
For technical support, please subscribe mail list linuxdriver@googlegroups.com and post there.
The url is
#
加载模块：
modprobe hello
modprobe globalmem globalmem_major=250
modprobe globalfifo globalfifo_major=251
skyeye对insmod的支持有些问题，加载模块时会出现：
# modprobe hello
Unable to handle kernel paging request at virtual address bf000000
pgd = c05f0000
[bf000000] *pgd=00000000
Internal error: Oops: 807 [#1]
Modules linked in:
CPU: 0 Not tainted (2.6.31.6-svn79 #21)
PC is at __memzero+0x24/0x80
LR is at 0x0
pc : [] lr : [<00000000>] psr: 20000013
sp : c182bf0c ip : 00000000 fp : 00000005
r10: c2807230 r9 : c2807000 r8 : c2807388
r7 : 00000004 r6 : c2807168 r5 : 00000012 r4 : bf000000
r3 : 00000000 r2 : 00000000 r1 : 00000464 r0 : bf000000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 0000317f Table: c05f0000 DAC: 00000015
Process modprobe (pid: 795, stack limit = 0xc182a270)
Stack: (0xc182bf0c to 0xc182c000)
bf00: c005fba0 00000979 00000000 c2807518 c2807608
bf20: c28072dc c1139e60 c28078a0 00000010 000000c5 c2807388 c182a000 c2807630
bf40: 00000000 c008c178 00000171 00000000 0015ec79 00000287 00000001 00000008
bf60: 00000000 00000979 0015e2f0 00000000 0015e300 c002bf48 c182a000 00000000
bf80: 00000000 c0060878 c1c1a2c0 c1c2f3a0 00000003 00000979 0015e2f0 0015dfa8
bfa0: 00000080 c002bda0 00000979 0015e2f0 0015e300 00000979 0015e2f0 00000000
bfc0: 00000979 0015e2f0 0015dfa8 00000080 0015e2a0 0015dfbc 00000001 00000000
bfe0: bea65958 bea65948 000177f8 00009350 20000010 0015e300 ab081000 11000006
[] (__memzero+0x24/0x80) from [<00000000>] (0x0)
Code: e52de004 e1a0c002 e1a0e002 e2511040 (a8a0500c)
---[ end trace 1e19dcbb1e19dcba ]---
Segmentation fault
详见bug: 我们使用strace去寻找死在哪个系统调用：
# strace modprobe hello
execve("/sbin/modprobe", ["modprobe", "hello"], [/* 7 vars */]) = 0
uname({sys="Linux", node="lihacker", ...}) = 0
brk(0) = 0x15d000
brk(0x15dd02) = 0x15dd02
set_tls(0x15d4a0, 0x1573c0, 0, 0x1, 0x15d4a0) = 0
brk(0x17ed02) = 0x17ed02
brk(0x17f000) = 0x17f000
getuid32() = 0
chdir("/lib/modules") = 0
uname({sys="Linux", node="lihacker", ...}) = 0
chdir("2.6.31.6-svn79") = 0
open("/proc/modules", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40000000
read(3, ""..., 1024) = 0
close(3) = 0
munmap(0x40000000, 4096) = 0
lstat64("/etc/modprobe.conf", 0xbe846880) = -1 ENOENT (No such file or directory)
lstat64("/etc/modprobe.d", 0xbe846880) = -1 ENOENT (No such file or directory)
open("modules.dep", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=17141, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40001000
read(3, "/lib/modules/2.6.31.6-svn79/kerne"..., 1024) = 1024
read(3, "nel/net/netfilter/x_tables.ko\n/li"..., 1024) = 1024
read(3, "/lib/modules/2.6.31.6-svn79/kerne"..., 1024) = 1024
read(3, "/net/netfilter/xt_esp.ko: /lib/mo"..., 1024) = 1024
read(3, "ables.ko /lib/modules/2.6.31.6-sv"..., 1024) = 1024
read(3, "es/2.6.31.6-svn79/kernel/net/netf"..., 1024) = 1024
read(3, ".6-svn79/kernel/net/netfilter/nf_"..., 1024) = 1024
read(3, "b/modules/2.6.31.6-svn79/kernel/n"..., 1024) = 1024
read(3, "etfilter/nf_conntrack_ipv4.ko /li"..., 1024) = 1024
read(3, ".6.31.6-svn79/kernel/net/netfilte"..., 1024) = 1024
read(3, "defrag_ipv4.ko\n/lib/modules/2.6.3"..., 1024) = 1024
read(3, "tfilter/nf_conntrack_ipv4.ko /lib"..., 1024) = 1024
read(3, ".6-svn79/kernel/net/ipv4/netfilte"..., 1024) = 1024
read(3, "1.6-svn79/kernel/net/netfilter/x_"..., 1024) = 1024
read(3, "ib/modules/2.6.31.6-svn79/kernel/"..., 1024) = 1024
read(3, "ib/modules/2.6.31.6-svn79/kernel/"..., 1024) = 1024
read(3, "o:\n/lib/modules/2.6.31.6-svn79/ke"..., 1024) = 757
close(3) = 0
munmap(0x40001000, 4096) = 0
open("/lib/modules/2.6.31.6-svn79/kernel/drivers/char/driver_examples/hello.ko", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=2425, ...}) = 0
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\1\0(\0\1\0\0\0\0\0\0\0\0\0\0\0\210"..., 3072) = 2425
read(3, ""..., 647) = 0
close(3) = 0
init_module(0x15e300, 2425, ""Unable to handle kernel paging request at virtual address bf000000
pgd = c0620000
[bf000000] *pgd=00000000
Internal error: Oops: 807 [#1]
Modules linked in:
CPU: 0 Not tainted (2.6.31.6-svn79 #21)
PC is at __memzero+0x24/0x80
LR is at 0x0
pc : [] lr : [<00000000>] psr: 20000013
sp : c069ff0c ip : 00000000 fp : 00000005
r10: c2807230 r9 : c2807000 r8 : c2807388
r7 : 00000004 r6 : c2807168 r5 : 00000012 r4 : bf000000
r3 : 00000000 r2 : 00000000 r1 : 00000464 r0 : bf000000
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 0000317f Table: c0620000 DAC: 00000015
Process modprobe (pid: 796, stack limit = 0xc069e270)
Stack: (0xc069ff0c to 0xc06a0000)
ff00: c005fba0 00000000 00000000 c2807518 c2807608
ff20: c28072dc c1139240 c28078a0 00000010 00000000 c2807388 00000000 c2807630
ff40: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ff60: 00000000 00000979 0015e2f0 00000000 0015e300 c002bf48 c069e000 00000000
ff80: 00000000 c0060878 be846958 c002dbe0 00000000 00000979 0015e2f0 0015dfa8
ffa0: 00000080 c002bf0c 00000979 0015e2f0 0015e300 00000979 0015e2f0 00000000
ffc0: 00000979 0015e2f0 0015dfa8 00000080 0015e2a0 0015dfbc 00000001 00000000
ffe0: be846958 be846948 000177f8 00009350 20000010 0015e300 ebff1fc9 e3500000
[] (__memzero+0x24/0x80) from [<00000000>] (0x0)
Code: e52de004 e1a0c002 e1a0e002 e2511040 (a8a0500c)
---[ end trace 1e19dcbb1e19dcba ]---
+++ killed by SIGSEGV +++
很明显，死在内核的linux-2.6.31/kernel/module.c的init_module()函数中,加上几个printk:
2453 SYSCALL_DEFINE3(init_module, void __user *, umod,
2454 unsigned long, len, const char __user *, uargs)
2455 {
2456 struct module *mod;
2457 int ret = 0;
2458
2459 printk("%s %d\n", __func__, __LINE__);
2460
2461 /* Must have permission */
2462 if (!capable(CAP_SYS_MODULE) || modules_disabled)
2463 return -EPERM;
2464
2465 +printk("%s %d\n", __func__, __LINE__);
2466
2467 /* Only one module load at a time, please */
2468 if (mutex_lock_interruptible(&module_mutex) != 0)
2469 return -EINTR;
2470
2471 +printk("%s %d\n", __func__, __LINE__);
2472
2473 /* Do all the hard work */
2474 mod = load_module(umod, len, uargs);
2475 if (IS_ERR(mod)) {
2476 mutex_unlock(&module_mutex);
2477 return PTR_ERR(mod);
2478 }
2479
2480 +printk("%s %d\n", __func__, __LINE__);
2481
再次运行:
# modprobe hello
sys_init_module 2459
sys_init_module 2465
sys_init_module 2471
Unable to handle kernel paging request at virtual address bf000000
pgd = c05f0000
[bf000000] *pgd=00000000
Internal error: Oops: 807 [#1]
Modules linked in:
从打印信息可以看出，panic发生在load_module函数，既然"sys_init_module 2471"被打印而"sys_init_module 2480"未打印。 继续跟进load_module()，直到最后发现内核崩溃在memset(ptr, 0, mod->core_size);：
static noinline struct module *load_module(void __user *umod,
unsigned long len,
const char __user *uargs)
{
...
ptr = module_alloc_update_bounds(mod->core_size);
...
kmemleak_not_leak(ptr);
...
memset(ptr, 0, mod->core_size);
一路跟踪源代码，发现ARM的Kernel会将模块的内存申请在3G-16M到3G的区域，而skyeye在内核空间处理3G以下地址的时候，会发生错误:
"Unable to handle kernel paging request at virtual address bf000000"
因此，workaround掉这个bug:
Index: arch/arm/kernel/module.c
===================================================================
--- arch/arm/kernel/module.c (revision 87)
+++ arch/arm/kernel/module.c (working copy)
@@ -38,7 +38,7 @@
#ifdef CONFIG_MMU
void *module_alloc(unsigned long size)
{
- struct vm_struct *area;
+ /*struct vm_struct *area;
size = PAGE_ALIGN(size);
if (!size)
@@ -49,6 +49,9 @@
return NULL;
return __vmalloc_area(area, GFP_KERNEL, PAGE_KERNEL_EXEC);
+*/
+
+ return size == 0 ? NULL : kmalloc(size, GFP_KERNEL);
}
#else /* CONFIG_MMU */
void *module_alloc(unsigned long size)
@@ -59,7 +62,7 @@
void module_free(struct module *module, void *region)
{
- vfree(region);
+ kfree(region);
}
int module_frob_arch_sections(Elf_Ehdr *hdr,
由 于此workaround使用了kmalloc，如果内核模块很大，kmalloc申请的内存不够存放，则可以修改： include/linux/slab.h中的KMALLOC_SHIFT_HIGH宏定义。另外，此workaround成立的条件是mem=32M或 小于32M。 现在我们可以自由地加载模块了，看看结果：
加载模块：
# modprobe hello
Hello World enter
# modprobe globalmem globalmem_major=250
# modprobe globalfifo globalfifo_major=251
查看加载的模块:
# lsmod
Not tainted
globalmem 3356 0 - Live 0xc0f66000
hello 1188 0 - Live 0xc1128000
globalfifo 4292 0 - Live 0xc182a000
查看设备：
# cat /proc/devices
Character devices:
1 mem
2 pty
3 ttyp
4 /dev/vc/0
4 tty
4 ttyS
5 /dev/tty
5 /dev/console
5 /dev/ptmx
7 vcs
10 misc
13 input
21 sg
29 fb
128 ptm
136 pts
204 s3c2410_serial
250 globalmem
251 globalfifo
建立结点：
# mknod /dev/globalmem c 250 0
# mknod /dev/globalfifo c 251 0
#
读写设备文件：
# echo "hello, cisco" > /dev/globalmem
written 13 bytes(s) from 0
# cat /dev/globalmem
read 4096 bytes(s) from 0
hello, cisco
# cat /dev/globalfifo &
# echo "hello,linux, I love you" > /dev/globalfifo
written 24 bytes(s),current_len:24
# read 24 bytes(s),current_len:0
hello,linux, I love you
本文用到的所有代码可通过svn获取：
svn checkout http://ldd6410.googlecode.com/svn/trunk/ ldd6410-read-only
本文实验已经做好的包位于：
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