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This is the first attempt at a complete boot loader for Linux on Sparc.
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Because of the lack of space on the bootblock, we have to do it in two
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steps, the first step is a very simple loader based on Peter Zaitcev's
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silo (we will call this the first stage loader) which should fit in 512B
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and its sole purpose is to load a more complete bootstrap loader, herein
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refered to as the second stage boot loader. The cool thing about the
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second stage loader we implemented is that it makes use of the ext2
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library (provided with the ext2fs tools) and some ufs code, and thus
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allows the loader to access any file on a ext2 fs and ufs, uses silo.conf,
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handles gunzipping and a lot of other things. This is different from
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Linux/i386 lilo which needs a map for each kernel. In silo we just keep
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one map file for the second stage loader, we don't expect you to be
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changing the second stage loader on your daily routine (you can do so, you
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will just need to use a tool to reinstall the maps).
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There are two distinct versions of the Sun EPROM, those before 2.0 ("old")
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and those of 2.0 and later ("new"). Unfortunately these details are
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visible at various points. With old proms, the device is specified as
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dev(X,Y,Z) [e.g. sd(0,3,1)] where dev is the device (normally sd), X is
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the controller, Y is the unit number, and Z is the partition number. Note
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that numbers start at 0, rather than Linux's convention of starting at 1,
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so sd(0,3,1) is /dev/sda2. Note also that many systems have the "first"
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disk (sda) as unit 3. With new proms, the device is specified in "open
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boot prom" format, e.g. /iommu/sbus/espdma/esp/sd@1,0 is target 1, LUN 0
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and /sbus/esp@0,800000/sd@3,0 is target 3, LUN 0.
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Due to a bug in some (all??) v2 PROMs (what about v0??) all the files
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which SILO can load must be below a magic boundary 1GB from the start of
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the disk (not from start of the partition). The easiest way is to put your
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/ filesystem completely inside first 1GB (and if you want to boot other OS
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on the same harddisk, put their / partitions under that boundary as well).
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Then just make sure you always leave the images you want to boot in those
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During the installation, SILO saves the original boot loader under a user
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especified file name, so, when silo prompts for a kernel name it is
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possible to load the original boot loader, either by adding it to your
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silo.conf or by typing its path on your SILO command line. Assuming the
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original boot block is stored in boot/old.b on partition 4, it can be
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accessed by having silo.conf containing:
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bootblock = 4/boot/old.b
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(old proms need "other = sd(0,3,0) bootblock = sd(0,3,3)/boot/old.b") or
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by typing 1 bootblock=/boot/old.b on your SILO command line.
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There is a magic image name `halt' that gets you back to the prom, and
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`help' displays some help text.
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If you wan to uninstall SILO, restore the original blocks by running e.g.
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dd if=/boot/old.b of=/dev/sda bs=512 seek=1 count=15
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You need all the proper compilers and linkers for Linux/SPARC native ELF
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compile, if you want to compile SILO yourself. But the standard
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distribution comes with all the necessary binaries.
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Under the boot, etc and sbin subdirs you will find all the programs
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already compiled and ready to run on Linux/SPARC. Those three directories
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should be probably copied to your /boot, /etc and /sbin on your root
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partition to make things easy. Then you just run /sbin/silo and if /boot
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doesn't contain old.b file yet, your old loader (usually sunos or solaris)
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will be copied there and silo will be installed. Bootblocks will be
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installed after the label of the disk which contains your second.b and
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silo.conf (both have to be on the same physical disk), e.g. if second.b is
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on /dev/sda5 and silo.conf on /dev/sda1, bootblocks will be installed into
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/dev/sda. In case you are creating a new root file system (e.g. your
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current root filesystem is nfs and you are setting up an ext2 root
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filesystem in /mnt), then you should run silo after installing boot, etc
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and sbin directories into /mnt/boot, /mnt/etc and /mnt/sbin with the -r
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parameter, e.g. /mnt/sbin/silo -r /mnt
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The firts loader pumps you into the second one very quickly, printing
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letters SILO after some actions are performed. If it prints only some of
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these letters and then dies, it means some error happened, e.g. if it
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prints SIL it means that it loaded a second stage loader, but with wrong
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magic. Then SILO prints a boot: prompt. If you give silo arguments on the
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prom command line already, SILO will try to load it (image params). This
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image can be either a full name (described later) or alias or label of
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some image in case you have silo.conf.
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Otherwise SILO refers to your silo.conf file, which is similar the iX86
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lilo.conf with some additions and omissions (some are not needed, others
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are not implemented). To the boot: prompt, you can:
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1) wait for the timeout (if any) to expire, which loads the "default"
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2) press enter, which loads the "default"
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3) type "halt" to get back to prom
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4) type "help" to get some help
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5) type an alias or label present in silo.conf
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6) press TAB to list the label names and aliases in silo.conf
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7) type the full path of the image to load
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where the "default" is the image marked as default=image, or the first
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one. The last option is the only one if you have no silo.conf, and gives
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you much more freedom at the expense of more typing.
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The full image path name depend on the prom version, pre 2.0 being "old",
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and 2.0 and later being "new". Old ones have {promname} whereas later have
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{prompath;}{partition_number}, i.e. new ones accept
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{prompath;}{partition_number}/kernelname {kernel-args}
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or {prompath;}{partition_number}[beg-end] {args}
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whereas old ones accept
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{promname}/kernelname {kernel-args}
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or {promname}[beg-end]
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{prompath;} and {promname} are optional, defaulting to the device specified
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in the main section (before first image keyword) of silo.conf, or the boot
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With old proms, you type prom paths as dev(X,Y,Z) [e.g. sd(0,3,1)].
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With new proms, you type the open boot prom style strings such as
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/iommu/sbus/espdma/esp/sd@1,0 terminated with a semicolon (;) to specify disk.
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Then the partition can be specified, defaulting to the (optional) partition=Z
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line in the main section in silo.conf. /dev/sda2 is "2".
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For all proms, you specify a path to the image starting with a slash (/),
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starting for the root of the specified partition.
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Alternatively, you can load portions of physical disk by typing [B-E] instead
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of /kernelname where B is the offset of the first 512 byte block to load,
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and E is the last. Thus [1-16] will load 7680 bytes starting at offset 512.
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On newer prome, if the partition number is omitted, it defaults to 0, i.e. the
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In all cases, kernel args are optional.
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/sbin/silo will warn you if there are any problems, but you should ensure that:
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you need to start either first, or third (usually whole disk), or any other
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partition on cylinder 0 in your partition table.
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It is highly recommended, that your first partition (sda1) starts on cylinder 0
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(beginning of disk) and that third partition (sda3) is of type WHOLE_DISK and
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spans the entire disk, as these are conbentions which are often assumed.
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If you do not, you have to make sure that whenever you use fdisk to change a
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partition which starts at 0 (which usually includes deleted partitions) to
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something else, you must rerun /sbin/silo on that disk.
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If you keep sda1 and sda3 startng at offset 0, you don't need to do that.
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SILO from 0.6.5 up supports loading of Solaris kernels without using the
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saved boot loader. Either put into your silo.conf something like
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image = 4/kernel/unix
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label = solaris-single
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(the name is relative to /platform/your_platform_name_here/ in case of
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Solaris 2.5+), keyword solaris says that the kernel needs special handling
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(otherwise it won't be loaded). On the command line, you can either type
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somewhere between parameters a keyword solaris, or if the name is
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/kernel/unix, you don't have to type anything. You should have your solaris
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ufsboot in either /ufsboot or /platform/your_platform_name_here/ of the
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partition you're booting solaris from.
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SILO from 0.7.3 onwards supports a special syntax for conditionals in
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silo.conf: instead of writing image keyword, you write e.g. image[sun4c,sun4m]
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which means if the machine is sun4c or sun4m, that image will appear as is,
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otherwise it will be hidden. There cannot be any spaces in the whole keyword
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(ie. between "image", "[", the list of machines and trailing "]", machines
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have to be separated by commas, the machine names should be either case of
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sun4, sun4c, sun4d, sun4m, sun4e, sun4u.
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image[sun4] = /boot/vmlinux-sun4.gz
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image[sun4c,sun4d,sun4m] = /boot/vmlinux-sparc32.gz
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image[sun4u] = /boot/vmlinux-sparc64.gz
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To create a bootable floppy, you can use the romfs filesystem. It will allow
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you to squeeze files on the floppy more than you achieve e.g. with ext2, and
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you can use the dual sun4[cdm]/sun4u first stage bootblock.
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You need to use genromfs-0.3 and higher. It can be obtained from
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ftp://ftp.banki.hu/pub/linux/local/genromfs-0.3.tar.gz.
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Firstly, you should populate the tree for the floppy in some directory. Lets
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assume it is floppy/. Then copy the /boot/fd.b bootblock somewhere into the
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floppy/ tree, e.g. to floppy/boot/fd.b. Then make sure you have the right
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silo.conf in the tree as well, and do:
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genromfs -d floppy/ -f /dev/ram -A 2048,/.. -a 512 -V 'My installation disk'
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mount -t romfs /dev/ram /mnt
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silo -r /mnt -F -i /boot/fd.b -b /boot/second.b -C /etc/silo.conf
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dd if=/dev/ram of=floppy.img bs=1440k count=1
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and you're done. -i defaults to /boot/fd.b for romfs floppies, -b defaults
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to /boot/second.b, -C to /etc/silo.conf. The -A 2048,/.. argument to romfs
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is required so that you have enough space for the first stage loader and
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-a 512 is required because of the internal implementation of romfs in
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second stage loader (but even if that changes, it would be required at
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least for /boot/second.b anyway).
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To create a bootable flash image for JavaStation-NC or JavaStation-E equiped
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with flash, populate flash/ directory with boot/ieee32.b, boot/second.b,
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etc/silo.conf, boot/proll.img and boot/vmlinux.gz:
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dd if=/dev/zero of=flash.img bs=1k count=1
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genromfs -a 512 -f romfs.img -d flash/
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cat romfs.img >> flash.img
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losetup /dev/loop0 -o 1024 flash.img
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mount -t romfs -o ro /dev/loop0 /mnt
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silo -J flash.img -i /boot/ieee32.b -r /mnt
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losetup -d /dev/loop0
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All the code is under GPL.
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* (DONE) Redo filesystem support so it is easier to plug in more
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* (All except ufs done) Add ls support for more filesystems
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* Fix ls so you can do "ls -l /some/file", since ls only works on
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directories right now.
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* Someway to cache the filesystems, so we don't have to
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open/read/close on every access to them.
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* More silo.conf keywords/commands
added
removed
docs/README
