Hi, Bellard (and others interested in the use of dd.exe, the Windows version of the Linux dd command, for creating bootable USB sticks from hybrid Slitaz iso files).
I emailed some questions to John Newbigin, the author of the version of dd.exe that I have been using.
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[John Newbigin | ITS Senior Analyst / Programmer
Faculty of Information and Communication Technologies
ITS | Swinburne University of Technology | Melbourne, Australia
O: EN306 | T: +61 3 9214 8185 | M: +61 410 569 362
E: jnewbigin@swin.edu.au]
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Here are my questions and his replies:
> Hi, John.
>
> I am trying to use dd.exe to put hybrid iso files of various linux
> distros onto pendrives from an Asus EeePC 1000HA netbook whose BIOS
> will boot from USB removable media. No luck so far, but I am studying
> your documentation at http://www.chrysocome.net/dd and have a few
> questions:
>
> Am I correct that the of= address for a removable usb device can
> be in the form \\.\x: ? Or must it be in the long form as \hardrive1\ ?
There are 2 syntaxes you can use. UNC or John's invention.
\\. is a UNC standard (you know about \\servername, well \\. says the
local computer). From there, Microsoft allows you to specify driver
letters, but drive letters are normally attached to filesystems which
are attached to partitions, not disks.
If you want to talk to a disk (other than a floppy disk or CD) then you
can't use \\.
But you can use my way which is based on the NT Native IO path.
In your case, I am pretty sure you will have to use the format
\\?\Device\Harddisk<X>\Partition0
You just have to work out the value for X. dd can try and do this for
you if you specify
od=x: (This means, find the disk for the partition mounted on x:)
> When if= an iso file on the hard drive, must the --size operator
> necessarily be used to keep dd from reading beyond the end of the
> file?
No. --size is only needed for block devices on older windows OS (before
Microsoft realised that knowing the size of a disk was important).
> What about controlling the size of the read out? In some
> instances, dd has filled a 4Gb pendrive with the command: dd
> if=xxxx.iso of=\\.\e: when the iso file was 125Mb.
I don't know, but it is possible because you are talking to the
filesystem driver and not the disk. \\.\e: is not where you want to
write to (at least, not before you unmount the filesystem).
> When of= FAT32-formatted usb removable media like a pendrive, will
> dd overwrite the boot sector, specifically the bytes reserved for the
> MBR?
Yes, if you tell it to (the MBR is the first sector of the disk (not the
partition).
> In your documentation you wrote:
>
> "... --size will tell dd to figure out the size of the device and
> make sure it does not read past that point. This is important for USB
> sticks which stop working if you read past the end of them."
>
> Query: Does this apply to the output file as well as the input
> file?
The process will stop when the end of the input is detected or there is
an error so it should not matter the size of the output.
> Query: If it does apply to the output file, and this has happened to
> my USB stick, will re-formatting the stick correct the problem?
All you need to do is unplug the USB stick and plug it back in.
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I Hope this is of interest.
Cheers!
Mike
