On Fri, Jun 25, 2004 at 10:53:45AM -0400, Jeremy Katz wrote: > On Thu, 2004-06-24 at 15:40 -0500, Matt Domsch wrote: > > Patch below against 2.6.7-bk(current) gives mbr_signature for first > > six BIOS disks. > > Seems to work, at least for two (all that I have handy on a test machine > right now). Cool. I realized last night that we sell servers with 12 disks in the main 7U chassis, not counting any external storage. So I'm reworking to code to allow storing MBR signatures for up to 16 disks. There's no real BIOS limitation at 16 or lower, but in practice it's rare to see more BIOS disks than this, and it takes 4 bytes of the real mode boot_params block per signature we might want to store, so I don't want it to get out of hand. > Unfortunately, the mbr_signature on both of those disks > (and the sig on the first from before rebooting into the newer kernel) > is 0x00000000. So I guess these don't have any guarantee of uniqueness? Right. The uniqueness guarantee has to come from whatever writes the signatures to the disk in the first place. There should have been in Rez's code a little chunk which, when it detects non-uniqness among the disks visible to Linux, it writes unique signatures to those disks, then reboots, such that when we restart, all the disks have unique signatures. fdisk and parted presently always write zeros to the 4-byte signature field at offset 0x1b8 in the MBR. Dell's factory install tools will write a unique signature to each BIOS-visible disk, so we're good there. Anaconda will need similar code. Thanks, Matt -- Matt Domsch Sr. Software Engineer, Lead Engineer Dell Linux Solutions linux.dell.com & www.dell.com/linux Linux on Dell mailing lists @ http://lists.us.dell.com
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