Boot Disk

[Rick Stevens]

Phil Schaffner wrote:
> On Thu, 2004-02-05 at 13:38, Bevan C. Bennett wrote:
> 
>>Michael Gargiullo wrote:
>>
>>>How do I format a floppy to accept the over-sized fedora boot image?
>>>
>>>I've tried mkbootdisk --size 1400 --device /dev/fd0 2.4.22-1.2149.nptl
>>>
>>>But it's still creating an image thats too large
> 
> 
> You're going the wrong direction - standard size is 1440 and the kernel
> already won't fit.
> 
> Try one or more of the following sizes, but the only one I've ever
> gotten to work is 1722 - seems to depend on specific floppy/BIOS
> combination:
> 
> [prs at radar0 prs]$ ll /dev/fd0u1[67]*
> brw-rw----    1 prs      floppy     2, 124 Sep 15 09:40 /dev/fd0u1660
> brw-rw----    1 prs      floppy     2,  44 Sep 15 09:40 /dev/fd0u1680
> brw-rw----    1 prs      floppy     2,  60 Sep 15 09:40 /dev/fd0u1722
> brw-rw----    1 prs      floppy     2,  76 Sep 15 09:40 /dev/fd0u1743
> brw-rw----    1 prs      floppy     2,  96 Sep 15 09:40 /dev/fd0u1760
> brw-rw----    1 prs      floppy     2, 116 Sep 15 09:40 /dev/fd0u1840
> brw-rw----    1 prs      floppy     2, 100 Sep 15 09:40 /dev/fd0u1920 
> For example:
> # fdformat /dev/fd0u1722
> # mkbootdisk --size 1722 --device /dev/fd0u1722 2.4.22-1.2149.nptl
> Alternatively, build a trimmed-down custom kernel that will fit a 1440
> floppy.
> 
> 
>>In the images directory of your fedora distribution should be several files:
>>
>>bootdisk.img - floppy sized boot image
>>drvnet.img - floppy sized image with extra network drivers
>>drvblock.img - floppy sized image with extra block device drivers
>>boot.iso - CD sized boot image with drivers included
>>
>>They can be found, for example, at 
>>ftp://rpmfind.net/linux/fedora/core/1/i386/os/images
>>
>>To put the boot image on a floppy:
>>% dd if=bootdisk.img of=/dev/fd0 bs=1024
> 
> 
> The above would work for installation boot, but seems he might want to
> boot a more current kernel.
> 
> Backing up a step, what is the real objective?  Is a boot floppy with a
> kernel required, or could the objective be satisfied by having (possibly
> redundant) kernels on hard disk and making a GRUB boot (or LILO - won't
> get into religious discussions) boot floppy?

Standard kernels will not fit on a floppy.  You need to build a
kernel that has NOTHING in it (fully modular) except maybe the IDE
driver, and build an initrd that has ONLY the modules you really need to
get the root filesystem on line (the SCSI stuff if you use SCSI and
perhaps ext3fs if you use the ext3 filesystem).
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- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-  You know you've landed gear-up when it takes full power to taxi.  -
-                                                -- Chuck Yeager     -
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