> -----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. > > -- > -GeneHi 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
On Fri, May 20, 2016 at 11:14 PM, Tal Lubko <tallubko at yahoo.com> wrote:> > >> -----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.What about the real OS's logs? What kind of a log? timestamps of executing a COM32 and perhaps what command executed? Reboot count? A single entry of something?> 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.I'd say the ADV is likely not appropriate for this.> BTW: Where can I find some explanation about ADV and --once parameter?For --once: http://www.syslinux.org/wiki/index.php?title=Install#options -- -Gene
> -----Original Message----- > From: Gene Cumm [mailto:gene.cumm at gmail.com] > Sent: Saturday, May 21, 2016 4:44 PM > To: Tal Lubko > Cc: For discussion of Syslinux and tftp-hpa > Subject: Re: [syslinux] Syslinux fwrite support > > On Fri, May 20, 2016 at 11:14 PM, Tal Lubko <tallubko at yahoo.com> wrote: > > > > > >> -----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. > > What about the real OS's logs? What kind of a log? timestamps of > executing a COM32 and perhaps what command executed? Reboot count? A > single entry of something? > > > 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. > > I'd say the ADV is likely not appropriate for this. > > > BTW: Where can I find some explanation about ADV and --once > parameter? > > For --once: > http://www.syslinux.org/wiki/index.php?title=Install#options > > -- > -GeneHi Gene Thanks a lot for your help. OS's log won't do the job but raw writing sectors is good enough. I think I understand the --once option but there aren't many details about it (for example where it is stored). I also couldn't find any detailed documentation about the ADV option. Tal