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HOW TO MAKE A SPARC BOOTABLE CDROM (NEW)
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SILO may be used to create a bootable CDROM for sparc. At the moment it will
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support booting on sun4c, sun4m, sun4d and sun4u machines only.
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A CDROM is booted on Sparc by issuing following commands in the PROM
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(depending on PROM version - v0 is PROM with major versions 0, found
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on sun4c only, v2 is PROM with major versions 2 or 3, found on some newer
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sun4c and all sun4m and sun4d machines) and the same applies to P1275 PROMs
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found in the 64bit UltraSparc machines:
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(cdrom is actually alias to /iommu/sbus/espdma/esp/sd@0,6:d or something
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As Solaris has different kernels for each architecture, the PROM boots by
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default from different "partitions" on the CD depending on the
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architecture of the machine (that's e.g. the :d in the cdrom alias on v2
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PROM). That partition table is stored in the first 512 bytes of the CD
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(with exactly the same format as partition tables on Sparc disks), so you
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can use SparcLinux fdisk program to look into that partition table.
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SparcLinux bootable CDROMs have a partition table where all partitions
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point to the main iso9660 image, starting from offset 0 to the end of the
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image. The only value PROM looks at is starting offset, so that it will
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boot on all machines correctly. In the boot process PROM finds start of
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the boot partition (in SILO's case it is always 0) and loads 7680 bytes
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from offset 512 in that partition. Fortunately iso9660 has the first 32KB
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(16 sectors) reserved for OS use, so that the partition table and
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bootblock can be safely stored there. As SILO is longer in size than those
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32KB (eventhough it is compressed), it puts its first stage loader in
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there and puts its second stage loader somewhere in the iso9660
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SILO 1.3.0 and up now uses the new isofs.b boot block for CD's. The old
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boot block required a patched mkisofs. This new boot block can be passed
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to stock mkisofs as the generic boot block. Adding the sparc-boot option
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will ensure that mkisofs adds the needed sun partition table.
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You should first prepare the tree you'd like to have on the CD. The only
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requirement is that you put boot/second.b from SILO distribution into
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/boot in the tree and edit the appropriate /boot/silo.conf in the tree. The
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isofs.b boot block does not need to be in the CD tree.
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This is VERY important. The isofs.b boot block is hard wired to look for
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second.b in /boot on the iso9660 image. The silo.conf has to be located in
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/boot aswell, since isofs.b will tell second.b that is the location.
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Note, you also need to make sure that you enable RockRidge extensions so
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that normal path lookups work. This has always been true for SILO's usage
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Once the tree is prepared, just do:
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mkisofs -G /boot/isofs.b -B ... -r -o IMAGENAME DIRECTORY_TREE
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and you're done. The "..." to the -B option tells it to make the generic
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isofs.b boot block the only image for all sparc-boot partition pointers.
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If you have any problems, mail silo-general@lists.sparc-boot.org
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first-isofs/README.SILO_ISOFS
