Is there a method to reboot a memdisk (floppy) image? I'm working on a DOS-based installation floppy that needs to repartition the hard disk prior to proceeding. DOS will only recognize the updated partition table after a reboot, but I'd like to be able to save information to the currently loaded memdisk floppy disk and simply reboot the image. Possible? I haven't had any luck with pboot, loadlin (for reasons discussed in the archives), or other programs I have available. I would think this is possible as the memdisk provided RAM disk is loaded prior to DOS. Am I missing something here? Any insights would be appreciated. - Rick
To reboot --------- You can write a really small program to do this. Create a file called "reboot.com". The assembly code should be JMP FFFF:0000 thats it. This location contains the BIOS code which reboots the machine. You should be able to create this using the "debug.exe" utility in three lines. If you are unable to do this, let me know, I will try to get the .COM file. To save information ------------------- No, you cannot make any changes to the image, when you boot off the memdisk image. Depending on what information you want to save and what it is for, you might be able to something about it. - Murali Puckett, Richard H. wrote:> Is there a method to reboot a memdisk (floppy) image? > > I'm working on a DOS-based installation floppy that needs to repartition the hard disk > prior to proceeding. DOS will only recognize the updated partition table after a reboot, but > I'd like to be able to save information to the currently loaded memdisk floppy disk and > simply reboot the image. Possible? > > I haven't had any luck with pboot, loadlin (for reasons discussed in the archives), or other > programs I have available. I would think this is possible as the memdisk provided RAM disk > is loaded prior to DOS. Am I missing something here? > > Any insights would be appreciated. > > - Rick > > > _______________________________________________ > SYSLINUX mailing list > Submissions to SYSLINUX at zytor.com > Unsubscribe or set options at: > http://www.zytor.com/mailman/listinfo/syslinux > Please do not send private replies to mailing list traffic. > >
Thanks for the information. I have a "reboot" program, but I was looking for a way to reuse the floppy image already loaded by memdisk -- to reload the floppy boot sector and re-bootstrap DOS off the virtual floppy. I suspect that even if I am able to actually execute this, that DOS will complain. I was looking for a way for the user to enter some configuration information, re-partition (and reboot), and continue with the installation. I presently do this from an actual bootable floppy, but have a new requirement is to support a floppyless boot by booting from a CD-ROM (in floppy emulation mode) which makes the floppy image read-only and persistent writable storage unavailable (pre-repartition anyway). Looks like I'll have to pursue other avenues of thought on this (like Windows PE or Linux) that support dynamic repartitioning w/o requiring rebooting. Thank you again. - Rick -----Original Message----- From: Murali Krishnan Ganapathy [mailto:gmurali at cs.uchicago.edu] Sent: Tuesday, April 05, 2005 8:00 PM To: Puckett, Richard H. Cc: syslinux at zytor.com Subject: Re: [syslinux] memdisk - reboot loaded image To reboot --------- You can write a really small program to do this. Create a file called "reboot.com". The assembly code should be JMP FFFF:0000 thats it. This location contains the BIOS code which reboots the machine. You should be able to create this using the "debug.exe" utility in three lines. If you are unable to do this, let me know, I will try to get the .COM file. To save information ------------------- No, you cannot make any changes to the image, when you boot off the memdisk image. Depending on what information you want to save and what it is for, you might be able to something about it. - Murali Puckett, Richard H. wrote:> Is there a method to reboot a memdisk (floppy) image? > > I'm working on a DOS-based installation floppy that needs to repartition the hard disk > prior to proceeding. DOS will only recognize the updated partition table after a reboot, but > I'd like to be able to save information to the currently loaded memdisk floppy disk and > simply reboot the image. Possible? > > I haven't had any luck with pboot, loadlin (for reasons discussed in the archives), or other > programs I have available. I would think this is possible as the memdisk provided RAM disk > is loaded prior to DOS. Am I missing something here? > > Any insights would be appreciated. > > - Rick > > > _______________________________________________ > SYSLINUX mailing list > Submissions to SYSLINUX at zytor.com > Unsubscribe or set options at: > http://www.zytor.com/mailman/listinfo/syslinux > Please do not send private replies to mailing list traffic. > >
Murali, Thanks for the suggestion, I'll check out the link you provided. - Rick -----Original Message----- From: Murali Krishnan Ganapathy [mailto:gmurali at cs.uchicago.edu] Sent: Wednesday, April 06, 2005 12:14 PM To: Puckett, Richard H. Cc: syslinux at zytor.com Subject: Re: [syslinux] memdisk - reboot loaded image I had the exact problem some time ago, and my solution was the "magic cookie" approach. In my case, I was partitioning the hard disk in Linux and had to reboot (because I was partitioning for Windows installation). I write the information "boot into DOS next" in an unused portion of the hard disk and reboot. SYSLINUX then boots my com32 program, which reads this information off the hard disk and instructs SYSLINUX to boot directly into DOS. This autoboot code can be got from http://people.cs.uchicago.edu/~gmurali/gui/downloads.html - Murali H. Peter Anvin wrote:> Puckett, Richard H. wrote: > >> I was looking for a way for the user to enter some configuration >> information, re-partition (and reboot), and continue with the >> installation. >> > > The way to do this is repartition the disks, and then write to a sector > on the hard disk a "magic cookie" that you can then use for a different > boot selection. Unfortunately DOS *has* to be rebooted, so there is no > way to do that without. > > Linux would be a better choice, really, as you have already surmised. > > -hpa >
Quinn, Thanks for the pointer. I had seen something like this in my searches, but didn't follow up on it. Now that you've reminded me of my "miss", I'll be sure to check this out. Thanks again, - Rick -----Original Message----- From: syslinux-bounces at zytor.com [mailto:syslinux-bounces at zytor.com]On Behalf Of Quinn Sent: Thursday, April 07, 2005 6:39 AM To: syslinux at zytor.com Subject: Re: [syslinux] memdisk - reboot loaded image QEMM386.SYS has been using this technique for years. The feature is called Quickboot. I've tested it with memdisk and it works perfectly. Anything I write to the ramdisk is still there when using Quickboot - and as the name implies it is "quick". QEMM386 redirects the reboot handler for CTRL-ALT-DEL so when I press CTRL-ALT-DEL it skips POST and boots from the memdisk image in memory. :-) Quinn Marc Haisenko wrote:>On Wednesday 06 April 2005 02:00, Murali Krishnan Ganapathy wrote: > > >>To reboot >>--------- >>You can write a really small program to do this. >>Create a file called "reboot.com". The assembly code should be >> >>JMP FFFF:0000 >> >>thats it. This location contains the BIOS code which reboots the >>machine. You should be able to create this using the "debug.exe" utility >>in three lines. >> >>If you are unable to do this, let me know, I will try to get the .COM file. >> >> > >This would be a cold boot, then. To warm boot you'd have to store the 1234h in >the word at 0040:0072. It's been a few years since I've written x86 assembler >programs so I can't write it down in assembler :-) >C'ya, > Marc > > >_______________________________________________ SYSLINUX mailing list Submissions to SYSLINUX at zytor.com Unsubscribe or set options at: http://www.zytor.com/mailman/listinfo/syslinux Please do not send private replies to mailing list traffic.
I am trying to install syslinux inside bochs and I am having weird issues. Here is what I did 01) Install bochs 02) Download fdos (10MB hard disk image) 03) bochs now boots into freedos without any issues 04) use bximage (part of bochs) to create a floppy.img 05) boot into freedos (via bochs) and format A: 06) quit bochs 07) run make on syslinux sources 08) configure mtools to interpret floppy.img as A: 09) copy syslinux.com and ldlinux.sys to floppy.img (using mtools) 10) boot into freedos (via bochs) 11) At this point I see syslinux.com as well as ldlinux.sys in A: 12) I make a backup of ldlinux.sys to backup.sys (copy command in FreeDOS) 12) Now I execute "syslinux a:" and get a usage message "syslinux [-sfma] drive: [bootsectfile]" even though my syntax seems to be correct 13) I now try "syslinux -s a:" and get an error message "cannot read ldlinux.sys". 14) If I look at the directory contents, ldlinux.sys is no longer there! 15) When I try to copy backup.sys to ldlinux.sys and I get an error saying the file exists 16) Now I see that ldlinux.sys has been made hidden (dir /a lists it) but it has zero size. I can provide any other information you need. Also, can I install syslinux on C: directly? - Murali