[syslinux] Syslinux fwrite support

[Gene Cumm]

On Tue, May 17, 2016 at 2:39 AM, Tal Lubko via Syslinux
<syslinux at zytor.com> wrote:
> Hi
> Does Syslinux support fwrite for fat filesystem?Is it supported for other filesystem?As far as I understand the function exist but isn't fully implemented.Is that correct?
> I also found this thread that says about the samehttp://www.syslinux.org/archives/2011-August/017093.html
> Thanks,Tal

At this time, writing should only be supported for the ADV and raw
sectors unless you're writing to a file over the network from a
network boot like TFTP upload.  Writing to a filesystem beyond
strictly overwriting contents of existing files byte for byte involves
understanding allocation and checksum mechanisms involved.  To my
knowledge, no file system that Syslinux supports stores hashes of file
contents into the file system metadata.

Traditionally, Syslinux has taken the approach that we can not trust
the BIOS calls for any writes beyond the ADV.

Tal, what's the goal/use case for using fwrite()?  Is it perhaps
something that could be solved using the ADV?  For example, the --once
parameter to syslinux/extlinux changes the default for one boot.

-- 
-Gene