[Schemix-devel] Updates to Schemix

[Cory Cross]

Hi everyone (if there is more than one...),
   The short:
   I started updating Schemix for the 2.6 kernels. It compiles/runs 
fine (to my limited testing, anyway) without kallsyms/devfs sections 
included. However, kallsyms has changed drastically since 2.4, and there 
are many changes needed. DevFS has many more. I replace the 
kernel_module( name ) function to one that now works in my test module. 
The diff is attached. However, the new code doesn't actually need or use 
anything from kallsyms.

   What next:
   I will be working on kernel_lookup() next, but I need some help. I 
don't understand very well what the memory_reference struct is, so if 
someone can explain it to me I will be most gracious.

   About me:
   I am a student in Computer Engineering at the University with 
interests including low-level programming and embedded systems. I also 
find the LispOS project fascinating. These two come together for my 
reasons for interest in this project: 1. See if a garbage-collecting, 
buffer-overrun-preventing language like Scheme or Lisp can form 
effective low-level/kernel code in less time than C, and 2. Replacing 
init with a Lisp or Scheme interpreter and adding Schemix to the kernel 
would allow people to work on something LispOS-like from both userland 
and kernelland at the same time, without having to deal with details 
like boot code right away. I started working heavily on this project 
over the last few days because it is Christmas break and I go crazy if I 
have down time!

   The diff:
   It is applied against schemix.c in schemix-0.2.1

Thank you
   Cory Cross

1337c1337
< /* The next few functions were taken from modutils/examples. */
---
> /* The next few functions were created by Cory Cross */
1340,1341d1339
< extern const char __start___kallsyms[];
< extern const char __stop___kallsyms[];
1343,1376c1341,1342
< static struct module *local_module_list;
< 
< static void get_module_list(void)
< {
<       const struct kallsyms_header    *ka_hdr;
<       const struct kallsyms_section   *ka_sec;
<       const struct kallsyms_symbol    *ka_sym;
<       const char                      *ka_str;
<       int i;
<       const char *p;
< 
<       if (__start___kallsyms >= __stop___kallsyms)
<               return;
<       ka_hdr = (struct kallsyms_header *)__start___kallsyms;
<       ka_sec = (struct kallsyms_section *)
<               ((char *)(ka_hdr) + ka_hdr->section_off);
<       ka_sym = (struct kallsyms_symbol *)
<               ((char *)(ka_hdr) + ka_hdr->symbol_off);
<       ka_str =
<               ((char *)(ka_hdr) + ka_hdr->string_off);
< 
<       for (i = 0;
<            i < ka_hdr->symbols;
<            kallsyms_next_sym(ka_hdr, ka_sym), ++i) {
<               p = ka_str + ka_sym->name_off;
<               if (strcmp(p, "module_list") == 0) {
<                       if (ka_sym->symbol_addr)
<                               local_module_list = *((struct module 
**)(ka_sym->symbol_addr));
<                       break;
<               }
<       }
< }
< 
< /* Find a module by its name */
---
> /*Find a module by its name,
>   this function doesn't actually use any kallsyms-specific features*/
1379,1391c1345,1378
<       struct module *m;
<       get_module_list();
< 
<       if( strcmp( name, "kernel" ) == 0 )
<               for( m = local_module_list; m; m = m->next )
<                       if( *(m->name) == 0 )
<                               return m;
< 
<       for( m = local_module_list; m; m = m->next )
<               if( strcmp( name, m->name ) == 0 )
<                       return m;
< 
<       return NULL;
---
>   /*Pointers used to iterate through modules*/
>   struct module *itr,*holder;
>   /*Search string*/
>   char *search;
> 
>   /*If name is NULL, return NULL*/
>   if(!name)
>     return 0;
> 
>   /*The kernel has a special name,
>     so we need to change the search string to find it*/
>   if( strcmp( name, "kernel" ) == 0 ) {
>     search = vmalloc(2);
>     search[0] = (char)1;search[1] = (char)0;
>   }
>   else {
>     search = name;
>   }
> 
>   /*This construct is from linux/list.h*/
>   list_for_each_entry_safe(itr,holder,&THIS_MODULE->list,list) {
> 
>     /*If our search string matches the module name...*/
>     if( strcmp( search, itr->name ) == 0 ) {
>       if( strcmp( name, "kernel" ) == 0 )
>       vfree(search);
>       return itr;
>     }
>   }
> 
>   /*module not found...*/
>   if( strcmp( name, "kernel" ) == 0 )
>     vfree(search);
>   return 0;
1393a1381
> 
4612a4601
>         unsigned int n; /*used down below*/
4635c4624
<       unsigned int n;
---
>       /*unsigned int n; moved to above*/