Re: [PATCH 2.6.21] cramfs: add cramfs Linear XIP

[Carsten Otte <cotte@de.ibm.com>]

Richard Griffiths (wrs) wrote:
> One question I have is the difference in the two models. If I understand
> correctly the filemap_xip expects the ext2 to mount as XIP while the
> Linear Cramfs only enables XIP for apps that have the sticky bit set.
> Hence the Application XIP moniker.
> Does the filemap_xip expect the entire filesystem is XIP?
The file operations from filemap_xip are only effective if the struct 
file_operations vector refers to them (see ext2_xip_file_operations in 
fs/ext2/file.c as example). In oder to function proper, the 
corresponding address_space_operations vector needs to provide an 
implementation of get_xip_page (see ext2_get_xip_page in 
fs/ext2/xip.c). Both vectors are per inode, one can chose to have XIP 
for individual files in a file system.

so long,
Carsten