为什么mkcramfs 不等于 mkfs.cramfs

isnowran

用上述两个工具制作initrd.img，mkfs.cramfs做的可以引导， mkcramfs做的不能引导，他们有什么区别吗？系统里也没有cramfs相关的man，望指教。

OS:         RedHat 9.0
Kernel:   2.4.32

isnowran

cramfs的相关文档怎么就这么少？只是在内核文档里找到一篇关于它的说明

1. 
   
2.         Cramfs - cram a filesystem onto a small ROM
   
3. 
   
4. cramfs is designed to be simple and small, and to compress things well.
   
5. 
   
6. It uses the zlib routines to compress a file one page at a time, and
   
7. allows random page access.  The meta-data is not compressed, but is
   
8. expressed in a very terse representation to make it use much less
   
9. diskspace than traditional filesystems.
   
10. 
    
11. You can't write to a cramfs filesystem (making it compressible and
    
12. compact also makes it _very_ hard to update on-the-fly), so you have to
    
13. create the disk image with the "mkcramfs" utility.
    
14. 
    
15. 
    
16. Usage Notes
    
17. -----------
    
18. 
    
19. File sizes are limited to less than 16MB.
    
20. 
    
21. Maximum filesystem size is a little over 256MB.  (The last file on the
    
22. filesystem is allowed to extend past 256MB.)
    
23. 
    
24. Only the low 8 bits of gid are stored.  The current version of
    
25. mkcramfs simply truncates to 8 bits, which is a potential security
    
26. issue.
    
27. 
    
28. Hard links are supported, but hard linked files
    
29. will still have a link count of 1 in the cramfs image.
    
30. 
    
31. Cramfs directories have no `.' or `..' entries.  Directories (like
    
32. every other file on cramfs) always have a link count of 1.  (There's
    
33. no need to use -noleaf in `find', btw.)
    
34. 
    
35. No timestamps are stored in a cramfs, so these default to the epoch
    
36. (1970 GMT).  Recently-accessed files may have updated timestamps, but
    
37. the update lasts only as long as the inode is cached in memory, after
    
38. which the timestamp reverts to 1970, i.e. moves backwards in time.
    
39. 
    
40. Currently, cramfs must be written and read with architectures of the
    
41. same endianness, and can be read only by kernels with PAGE_CACHE_SIZE
    
42. == 4096.  At least the latter of these is a bug, but it hasn't been
    
43. decided what the best fix is.  For the moment if you have larger pages
    
44. you can just change the #define in mkcramfs.c, so long as you don't
    
45. mind the filesystem becoming unreadable to future kernels.
    
46. 
    
47. 
    
48. For /usr/share/magic
    
49. --------------------
    
50. 
    
51. 0       ulelong 0x28cd3d45      Linux cramfs offset 0
    
52. >4      ulelong x               size %d
    
53. >8      ulelong x               flags 0x%x
    
54. >12     ulelong x               future 0x%x
    
55. >16     string  >\0             signature "%.16s"
    
56. >32     ulelong x               fsid.crc 0x%x
    
57. >36     ulelong x               fsid.edition %d
    
58. >40     ulelong x               fsid.blocks %d
    
59. >44     ulelong x               fsid.files %d
    
60. >48     string  >\0             name "%.16s"
    
61. 512     ulelong 0x28cd3d45      Linux cramfs offset 512
    
62. >516    ulelong x               size %d
    
63. >520    ulelong x               flags 0x%x
    
64. >524    ulelong x               future 0x%x
    
65. >528    string  >\0             signature "%.16s"
    
66. >544    ulelong x               fsid.crc 0x%x
    
67. >548    ulelong x               fsid.edition %d
    
68. >552    ulelong x               fsid.blocks %d
    
69. >556    ulelong x               fsid.files %d
    
70. >560    string  >\0             name "%.16s"
    
71. 
    
72. 
    
73. Hacker Notes
    
74. ------------
    
75. 
    
76. See fs/cramfs/README for filesystem layout and implementation notes.
    

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