[syslinux] Syslinux fwrite support

[Tal Lubko]

> -----Original Message-----
> From: Gene Cumm [mailto:gene.cumm at gmail.com]
> Sent: Tuesday, May 17, 2016 1:07 PM
> To: Tal Lubko
> Cc: syslinux at zytor.com
> Subject: Re: [syslinux] Syslinux fwrite support
> 
> 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
Hi

The goal is some kind of boot log.
I understand it is possible by using raw sectors writing.
I couldn't find much documentation about ADV, but my guess that it wouldn’t do the job.
BTW: Where can I find some explanation about ADV and --once parameter?

Tal