[BusyBox] Re: BusyBox insmod problem. Global variables badly initialized.

[Christian Grigis]

Hello,

On Thu Mar 28 01:28:05 2002, <Frederic.Goddeeris at siemens.atea.be> wrote:
> Hi,
> 
> I have been struggling with global variables that are not always correctly
> initialized in kernel modules and have been posting reports to ppclinux-dev
> about this.
> 
> Somebody reported that he had seen the same issue while somebody else
> reported he could not reproduce the problem. Today I discovered that when I
> use the original insmod instead of the insmod in Busybox the issue seems
> solved...
> 
> This is the modules I used for testing:
> 
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/init.h>
> 
> char MyMemSpace[2*0x100];
> char *MemPointers[2] = {&(MyMemSpace[0]), &(MyMemSpace[0x100])};
> 
> typedef struct
> {
> 	char *szName;
> 	char *szName2;
> } MyStruct_t;
> 
> MyStruct_t MyStruct[] = {{"A", "A2"}, {"B", "B2"}};
> 
> int init_module(void)
> {
> 	printk("TestDriver 3 Loaded\n");
> 
> 	printk("MyMemSpace: 0x%lx 0x%lx \n",  (long)&(MyMemSpace[0]),
> 	       (long)&(MyMemSpace[0x100]));
> 	printk("MemPointers: 0x%lx 0x%lx \n", (long)(MemPointers[0]),
> 	       (long)(MemPointers[1]));
> 
> 	printk("First Char is MyStruct[0].szName %c\n",
> 	       MyStruct[0].szName[0]);
> 
> 
> 	return -1;
> }
> 
> void cleanup_module(void)
> {
> 	return;
> }
> 
> With insmod of busybox I get:
> 	MyMemSpace: 0xc304a1ec 0xc304a2ec
> 	MemPointers: 0xc304a1ec 0xc304a3ec
> 	First Char is MyStruct[0].szName e 
> 
> With the regular insmod I get:
> 	MyMemSpace: 0xc304226c 0xc304236c
> 	MemPointers: 0xc304226c 0xc304236c
> 	First Char is MyStruct[0].szName A
> 
> I use HHL2.0 (2.4.2), gcc 2.95.3, Busybox 0.60.2
> 
> Can somebody help me solving this issue?
> 
> Thanks,
> Frederic 
 

I have been having the exact same problem on a similar environment (HHL2.0 PPC
w/kernel 2.4.2, gcc 2.95.3, latest CVS busybox), and also noticed that the
char pointers in a global struct were resolved correctly only with the 
standard insmod from modutils, but not with BusyBox's insmod.

Does anyone have more information about this? Is it a problem with BusyBox's
insmod or the kernel I am using?

Thank you very much for any help.

Regards,

-Christian
 
-- 
Christian Grigis			|	SMARTDATA SA
Software Engineer			|	PSE-A / EPFL
Phone: +41-21-693-84-98 		|	CH - 1015 Lausanne
mailto:christian.grigis at smartdata.ch	|	http://www.smartdata.ch