Clarification of IMFS
joel.sherrill at oarcorp.com
Fri Jun 9 13:54:32 UTC 2006
Steven Johnson wrote:
>Can I just confirm that my understanding of an aspect of the IMFS is
>IMFS has a file type called "LINEAR_FILE" and it is used primarily for
>the "TAR" loader. My understanding is, the TAR image is in memory
>somewhere, and the IMFS just points to the data of each file in the TAR,
>but doesn't contain the actual data itself, in the standard file blocks
>(of 128 bytes). Is there a size limit, for example, does the file block
>size, which normally limits the size of a file in the IMFS limit the
>maximum size of the LINEAR_FILE in the TAR, or is it unbounded.
The data stays in the linear format -- see imfs_load_tar.c around line 159.
It is treated as one chunk of data in the header.
If you ever open it successfully for write, it will be converted into a
RAM file. See memfile.c around 115. The file size limit would kick in
This was a really clever trick to support a "ROM fs" without a special
tool to create the image. :)
>The reason why I ask, is I want to implement my own loader, the file
>data in my system is not in TAR format, but it is linear. I would like
>to switch over to a traditional file system model, and linking them as
>LINEAR files seems like the expedient thing to do. The files, in this
>case, are read only.
More information about the users