Groups > linux.debian.user > #240120 > unrolled thread

Lock tab on SD card?

Started by	conover@rahul.net (John Conover)
First post	2021-09-18 19:40 +0200
Last post	2021-09-19 14:00 +0200
Articles	4 — 4 participants

Back to article view | Back to linux.debian.user

  Lock tab on SD card? conover@rahul.net (John Conover) - 2021-09-18 19:40 +0200
    Re: Lock tab on SD card? David Christensen <dpchrist@holgerdanske.com> - 2021-09-18 20:50 +0200
    Re: Lock tab on SD card? Dan Ritter <dsr@randomstring.org> - 2021-09-18 21:10 +0200
      Re: Lock tab on SD card? "Andrew M.A. Cater" <amacater@einval.com> - 2021-09-19 14:00 +0200

#240120 — Lock tab on SD card?

From	conover@rahul.net (John Conover)
Date	2021-09-18 19:40 +0200
Subject	Lock tab on SD card?
Message-ID	<CYMtH-4KS-3@gated-at.bofh.it>

Mounting an SD card with the lock tab enabled mounts as read only.

But can Linux still write to the SD card, under any circumstances?

    Thanks,

    John

-- 

John Conover, conover@rahul.net, http://www.johncon.com/

[toc] | [next] | [standalone]

#240121

From	David Christensen <dpchrist@holgerdanske.com>
Date	2021-09-18 20:50 +0200
Message-ID	<CYNzr-5lY-5@gated-at.bofh.it>
In reply to	#240120

On 9/18/21 10:28 AM, John Conover wrote:
> 
> Mounting an SD card with the lock tab enabled mounts as read only.
> 
> But can Linux still write to the SD card, under any circumstances?

My assumption is that the lock tab on SD cards is read by the controller 
inside the SD card, which then provides read-only or read-write mode.

I would test  the SD card in question to confirm.

David

[toc] | [prev] | [next] | [standalone]

#240122

From	Dan Ritter <dsr@randomstring.org>
Date	2021-09-18 21:10 +0200
Message-ID	<CYNSO-5HI-3@gated-at.bofh.it>
In reply to	#240120

John Conover wrote: 
> 
> Mounting an SD card with the lock tab enabled mounts as read only.
> 
> But can Linux still write to the SD card, under any circumstances?

Under *any* circumstances? Yes.

Those circumstances include:

- a broken lock position sensor on the SD card reader

- the SD card is actually a microSD card in an adaptor; moving
  it to a microSD reader or a different adaptor will work

- the reader has been altered away from spec

- the lock tab is moved

Note that Linux needs to remount a read-only filesystem to make
it read-write.

Now, what is the problem you are actually trying to solve?

-dsr-

[toc] | [prev] | [next] | [standalone]

#240145

From	"Andrew M.A. Cater" <amacater@einval.com>
Date	2021-09-19 14:00 +0200
Message-ID	<CZ3Ed-6Li-7@gated-at.bofh.it>
In reply to	#240122

On Sat, Sep 18, 2021 at 03:06:14PM -0400, Dan Ritter wrote:
> John Conover wrote: 
> > 
> > Mounting an SD card with the lock tab enabled mounts as read only.
> > 
> > But can Linux still write to the SD card, under any circumstances?
> 
> Under *any* circumstances? Yes.
> 
> Those circumstances include:
> 
> - a broken lock position sensor on the SD card reader
> 
> - the SD card is actually a microSD card in an adaptor; moving
>   it to a microSD reader or a different adaptor will work
> 
> - the reader has been altered away from spec
> 
> - the lock tab is moved
> 
> Note that Linux needs to remount a read-only filesystem to make
> it read-write.
> 
> Now, what is the problem you are actually trying to solve?
> 
> -dsr-
> 

I'll agree with all Dan has written: there's also the real annoyance and
difficulty that it is small and hard to see and invariably gets locked
when you least expect it and you're trying to work out why you can't copy
a file to an SD card to make it bootable :)

if you're worried about "Can Linux override a physical switch" - the answer
is no, in general terms.

All the very best, as ever,

Andy Cater

[toc] | [prev] | [standalone]

csiph-web

Lock tab on SD card?

Contents

#240120 — Lock tab on SD card?

#240121

#240122

#240145