Setting block.no_part_scan=no on sys-usb’s command line does not work

[Demi M. Obenour]

I am trying to disable automatic partition scanning in sys-usb,
and tried including block.no_part_scan=no in sys-usb’s kernelopts.
However, it had no effect. `block.no_part_scan=0` also doesn’t work.

Did I make a mistake in the command line?

Sincerely,

Demi

[unman]

On Fri, Dec 25, 2020 at 09:13:24PM -0500, Demi M. Obenour wrote:
> I am trying to disable automatic partition scanning in sys-usb,

> and tried including block.no_part_scan=no in sys-usb???s kernelopts.
> However, it had no effect. `block.no_part_scan=0` also doesn???t work.

>
> Did I make a mistake in the command line?
>
> Sincerely,
>
> Demi
>

no_part_scan=Y ?
test by writing to /sys/module/block/parameters/no_part_scan

[Rusty Bird]

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Hash: SHA512

unman:

> On Fri, Dec 25, 2020 at 09:13:24PM -0500, Demi M. Obenour wrote:
> > I am trying to disable automatic partition scanning in sys-usb,

> > and tried including block.no_part_scan=no in sys-usb’s kernelopts.
> > However, it had no effect. `block.no_part_scan=0` also doesn’t work.

> no_part_scan=Y ?
> test by writing to /sys/module/block/parameters/no_part_scan

Yes it's Y, but with 'block.no_part_scan=Y' in kernelopts, the VM will
fail to boot because now it can't find /dev/xvda3 (root) or /dev/xvdc1
(swap). So this parameter is intended to be set by writing Y to /sys
after the VM has booted.

Block device content is also parsed by udev scans for filesystems etc.
In Split dm-crypt, those scans are disabled by installing a udev rules
file which piggybacks on the kernel parameter:

https://github.com/rustybird/qubes-split-dm-crypt/blob/master/vm/rules.d/00-blockdev-parsing-disabled.rules

Rusty
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