Thread: OpenBSD LiveUSB
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Old 12th May 2009
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jggimi jggimi is offline
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USB mass storage is managed through sd(4). It is a virtual SCSI device, no matter if the device is flash memory or hard drive.

You can do a standard installation to any USB device, as long as it has sufficient capacity. Since it is treated as a hard drive, use an MBR on architectures that require them, as well as a standard disklabel.

If your BIOS permits booting from USB, nothing else is needed.

If your BIOS does not permit booting from USB, you just need a boot loader on some other media, such as: diskette, optical disc, or network.

The only changes I've made to LiveCD kernels are to point the root partition to cd0a. This is no longer necessary with 4.5, and is entirely unnecessary with sd devices. The major changes for read-only (live) media are not kernel. The changes, instead, are to /etc/rc. In general, one mounts a set of MFS filesystems for read/write.

Modern flash media is supposed to have good write lifespan, therefore, with modern BIOS and modern USB devices, the general recommendation is to treat your stick like a disk drive, and not worry.

Since most modern sticks are much larger than the storage used in tiny embedded systems, I don't think bowlfish is necessary. It's hard to find USB sticks with less than 1/2 GB of storage these days, and a complete i386 or amd64 system will fit in that with room to spare.
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