On 01/06/11 07:53, Rajat Sharma wrote: > Hi Sebastian, > > you guess for ELF header seems to be valid to me. When executables or > binaries are loaded memory, it is done through mmap call to the file, > and to understand what file is and what binary handler in kernel can > handle its section, kernel needs to know its header first, which is > within the first page of the header with fixed location for a magic > number (identifier for binary handler e.g. ELF handler which further > loads its other sections by reading section table). Note that there > are multiple binary format handles within the kernel e.g. ELF, A.OUT > which are tried sequentially to identify the file format. > > From the file system perspective, mmap does not use vfs_read or > vfs_write calls at all, thats why you don't see them. It directly > works on address space operations of an inode (file) to populate data > in page-cache. For a mmapped region, if you don't see a page in > memory, kenel page faults and tries to read-in the page using readpage > method of address_space_operations. Similarly when you modify a page, > writepage method is called, but since executables are accessed > read-only, you won't see writepage method getting called either. > > Hope this makes it clearer. Excellent, thank you! I find calls to readpages on file /lib/libc-2.11.2.so now. That may be the missing reads. Any ideas how get offset and length (like with vfs_read) for a certain page passed to readpage(file, page) ? Best, Sebastian _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
