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Any Relation Between A USB Stick Being Bootable (Or Not) -and- Fixed (Or Not ‘ Removable)


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This is with respect to the USB stick controller with a "flippable" bit that can tell OS whether the device is "removable" or "fixed".
And with my difficulty in getting removable HDD sticks to be seen as BIOS bootable.
Maybe some related setup restriction that is tripping me up?
Thanks

Edited by RUSerious
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Of course it depends on the specific stick controller AND on the specific BIOS.

Most of the sticks have a setting (called in jargon "removable" bit) that can be "flipped" by the Manufacturer Tool.

Whether a Manufacturer Tool is available or not (and if even minimal instructions/docs for its use exist) vary greatly on the specific make/model of the controller inside the stick.

Sandisk (that you mentioned in your other post) is a known exception for two reasons, their tools never leaked (AFAIK) and their controllers are not programmable via the USB connector (as well AFAIK they have on the PCB some contacts that can - presumably - be used with a TTL or similar serial adapter).

But - generally speaking - this "removable bit" does not in itself affect in any way the BIOS (and more generally "real mode") part of the booting, issues can happen later in the booting phase and/or in the way the OS behaves after booting.

If the manufacturer tool is available and you have the guts for it (a mistake in using it may well make the device not working anymore) setting the stick as "fixed" is a good idea, but there are filter drivers for Windows that can make the "flipping" at OS level, historically a driver called cfadisk.sys was made (originally for CF cards) then a couple similar ones came out dummydisk.sys and its "reversed version" rdummy.sys (making a fixed device removable), the most recent one is diskmod.sys that offers some other features:

http://reboot.pro/index.php?showtopic=9461

http://reboot.pro/topic/22249-diskmod/

Windows before 10 treated "removable" (USB) devices different from "fixed", i.e. the stick was either unpartitioned or - if partitioned - only one (first) partition would have been mounted/assigned a drive letter, so the filter driver was needed whenever multiple partitions were needed or wanted, one of the very few good things that Windows 10 did was to allow multiple partitions on removable media, so that nowadays cases where the filter driver is needed are rare.

Anyway all the above has historically been irrelevant when it comes to "booting" (defined for the scope of this post as the initial part of booting, up to the choices in the boot manager configuration files).

Problems in this early part usually derive from (not necessarily in order of relevance):
1) "wrong" HS geometry of the partitioning/formatting (almost anything partitioned under windows will be 255/63, which may or may not suitable)
2) errors in the MBR or PBR code or data
3) strange settings or quirks in the motherboard BIOS, including (but not limited to) "allergy" to specific MBR code, limits on geometry depending on size of the device, device size limits, and more, like needing two partitions on the stick

The above is about BIOS/MBR, I hate to say this but (with some exceptions) UEFI booting often has less issues as it does not usually suffer from #1 and #2 above.

You will need to describe the issues you are having and the specific sticks and motherboards involved (and of course the boot manager/OS you are trying to boot).

jaclaz

 

 

Edited by jaclaz
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Many thanks for your extensive replies jaclaz.  I’ve been using some ‘older’ HP laptops for the past several years now.  These have suspect USB drivers and were likely some of the earliest BIOS versions to offer UEFI options / support.  So I think you nailed down the cause of this issue and what led me to believe that IF controller’s "flippable" bit was set to "removable", THEN it could not be bootable.

I did try several variations with BOOTICE to see if any combination might work with my HP laptop / "removable" stick combo, but nothing worked. BOOTICE does however confirm that the sticks not bootable for me are set as "removable", and that those sticks that are bootable are set as “fixed”… in that BOOTICE designates "removable" setting with an RM# and the flip with an HD#.  And BOOTICE seems to treat both the same with respect to options available.

Thanks again for correcting me on this.

Edited by RUSerious
Edited to correct my grammar
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If the USB stick is new of the USB3 generation and the motherboard is old, there could be an incompatibility because at some stage it wants an USB 1 speed, which the USB3 device might not support.

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On BIOS, one of the things that "made a difference" was the presence of TWO (primary) partitions, If you check the RMPREPUSB, you will see how it has an option to make a second (tiny, one cylinder) hidden partition.

It is possible (but not given) that even the UEFI implementation on those motherboards is sensible to it, even if the GPT should only have one entry in partition table (the "protective" one) there is the possibility to make a "hybrid" partitioning, with the added second partition entry, no way to know if it will do anything, of course.

There is a nice page by Roderick Smith (author of Gdisk) about hybrid MBR's:

https://www.rodsbooks.com/gdisk/hybrid.html

There are other workarounds, check:

http://reboot.pro/index.php?showtopic=12436

it could also be that the "removable" bit is actually meaningful in your specific BIOS/UEFI.

jaclaz

Edited by jaclaz
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