perhaps the drive firmware presents the drive as bootable when first awakened .. to load driver like software .. or perhaps malware ...
On Fri, Jun 26, 2015 at 7:35 PM, jd1008 <jd1...@gmail.com> wrote: > > > On 06/26/2015 06:09 PM, Rick Stevens wrote: > >> On 06/26/2015 04:42 PM, jd1008 wrote: >> >>> >>> >>> On 06/26/2015 05:29 PM, Rick Stevens wrote: >>> >>>> On 06/26/2015 04:05 PM, jd1008 wrote: >>>> >>>>> >>>>> >>>>> On 06/26/2015 04:55 PM, Gordon Messmer wrote: >>>>> >>>>>> On 06/26/2015 02:51 PM, jd1008 wrote: >>>>>> >>>>>>> Just wondering about the bytes in the first sector which >>>>>>> you thought might be boot code that is confusing BIOS >>>>>>> to think that my usb drive is bootable. >>>>>>> The bytes you already saw are obviously not boot code. >>>>>>> >>>>>> >>>>>> What is obvious to you is not obvious to the CPU, which simply >>>>>> executes instructions. Everything in bytes is 0-446 is boot code, >>>>>> whether it does anything useful or not. >>>>>> >>>>> Fine! No argument there. >>>>> Where do device (or partition) labels reside? In the partitions? >>>>> >>>> >>>> fdisk- (dos-) style partition tables do not have partition labels. GPT >>>> partitions do. They are 72 bytes long, starting at offset 56 in the >>>> partition's entry in the partition table. >>>> >>>> The location of the partition table is given in an 8-byte value >>>> starting at offset 72 in the GPT header. Generally, they start at the >>>> second LBA (LBA1) on the disk and are 128 bytes long. >>>> >>>> Filesystem labels (regardless of DPT or GPT partitioning) are located >>>> in the filesystem's superblock(s). They are 16 bytes long starting at >>>> offset 120 in each copy of the superblock. >>>> >>> >>> OK. So if only GPT partitions have labels, >>> what does mlabel do (i.e. where does it place the label?). >>> >>> $ yum provides /usr/bin/mlabel >>> Loaded plugins: langpacks, refresh-packagekit >>> mtools-4.0.18-4.fc20.x86_64 : Programs for accessing MS-DOS disks >>> without mounting the disks >>> Repo : fedora >>> Matched from: >>> Filename : /usr/bin/mlabel >>> >> >> The location of a filesystem label (if supported) is dependent on the >> filesystem type, so perhaps I misled you a tad. Sorry! The 16-byte >> label area starting at offset 120 of the superblock I mentioned above >> is for ext2|3|4 filesystems. >> >> For FAT12 and FAT16 filesystems, the label is stored in an 11-byte area >> starting at offset 43 in the partition's header. For FAT32 filesystems, >> it's stored in an 11-byte area starting at offset 71 in the partition's >> header. >> >> You really can google this stuff yourself, you know. >> > I have been googling and read wikis. > None of them really explain clearly > If > 1. a drive has no bootable partitions and > 2. the boot code in the 1st 446 bytes does not exist (all nulls) > then > how does bios decide it is not bootable, move on to the next in the > sequence? > > As I have already indicated, bios is not moving on to the next > disk; in this case, the internal HD. > For bios to spend an eternity looking for the boot code on a non-bootable > drive tells me it is a bug, even if implemented according to specs (thus > the > specs themselves would be at fault). > I even read a passage that said something to the effect > ....."implementation dependent".... > > Of course, the dependency being based on different requirements or > different standards .... etc. > > Should have kept the darned page so I could give the URL. > > I recall Prof. Andrew /Tannenbaum's maxim: > The great thing about standards is that there are so many of them. > > > / > -- > users mailing list > users@lists.fedoraproject.org > To unsubscribe or change subscription options: > https://admin.fedoraproject.org/mailman/listinfo/users > Fedora Code of Conduct: http://fedoraproject.org/code-of-conduct > Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines > Have a question? Ask away: http://ask.fedoraproject.org >
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