/dev/bcache/by-uuid directory empty

/dev/bcache/by-uuid directory empty

[Nathan Dehnel]

I have modprobed bcache and registered the caches + backing drives
necessary to mount a volume on bcache:

root@guixrig ~/guix-configs/guixrig# ls /dev/bcache*
/dev/bcache0  /dev/bcache2  /dev/bcache4  /dev/bcache6  /dev/bcache8
/dev/bcache1  /dev/bcache3  /dev/bcache5  /dev/bcache7  /dev/bcache9

However, /dev/bcache/by-uuid is empty.
The manual https://www.kernel.org/doc/Documentation/bcache.txt states
that udev is necessary, and it is enabled:

root@guixrig ~/guix-configs/guixrig# herd status udev
Status of udev:
  It is started.
  Running value is 206.
  It is enabled.
  Provides (udev).
  Requires (root-file-system).
  Conflicts with ().
  Will not be respawned.

Is there something else I need to do to get the directory to populate?

Re: /dev/bcache/by-uuid directory empty

[Tobias Geerinckx-Rice]

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Nathan,

You may well be the first to (try to) use bcache on Guix System.

Nathan Dehnel 写道：
> The manual https://www.kernel.org/doc/Documentation/bcache.txt 
> states
> that udev is necessary, and it is enabled:

It says:

--8<---------------cut here---------------start------------->8---
bcache-tools now ships udev rules, and bcache devices are known to
the kernel immediately.
--8<---------------cut here---------------end--------------->8---

which is a bit more than that.  Guix doesn't ship bcache-tools 
(yet); are you using your own package?  If so, please consider 
sharing :-)

You'd have to add it to the RULES field of your system's 
UDEV-CONFIGURATION to make the system's udev ‘see’ the rules. 
Simply installing it or adding it to your system packages isn't 
enough.

The kernel docs continue:

--8<---------------cut here---------------start------------->8---
Without udev, you can manually register devices like this::

  echo /dev/sdb > /sys/fs/bcache/register
  echo /dev/sdc > /sys/fs/bcache/register

Registering the backing device makes the bcache device show up in
/dev; you can now format it and use it as normal.
--8<---------------cut here---------------end--------------->8---

Have you tried this?

Good luck,

T G-R

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Re: /dev/bcache/by-uuid directory empty

[Nathan Dehnel]

>which is a bit more than that.  Guix doesn't ship bcache-tools
(yet); are you using your own package?  If so, please consider
sharing :-)

I could try to make a package.

>Have you tried this?

Yes.

On Fri, Dec 18, 2020 at 8:13 AM Tobias Geerinckx-Rice <me@tobias.gr> wrote:
>
> Nathan,
>
> You may well be the first to (try to) use bcache on Guix System.
>
> Nathan Dehnel 写道：
> > The manual https://www.kernel.org/doc/Documentation/bcache.txt
> > states
> > that udev is necessary, and it is enabled:
>
> It says:
>
> --8<---------------cut here---------------start------------->8---
> bcache-tools now ships udev rules, and bcache devices are known to
> the kernel immediately.
> --8<---------------cut here---------------end--------------->8---
>
> which is a bit more than that.  Guix doesn't ship bcache-tools
> (yet); are you using your own package?  If so, please consider
> sharing :-)
>
> You'd have to add it to the RULES field of your system's
> UDEV-CONFIGURATION to make the system's udev ‘see’ the rules.
> Simply installing it or adding it to your system packages isn't
> enough.
>
> The kernel docs continue:
>
> --8<---------------cut here---------------start------------->8---
> Without udev, you can manually register devices like this::
>
>   echo /dev/sdb > /sys/fs/bcache/register
>   echo /dev/sdc > /sys/fs/bcache/register
>
> Registering the backing device makes the bcache device show up in
> /dev; you can now format it and use it as normal.
> --8<---------------cut here---------------end--------------->8---
>
> Have you tried this?
>
> Good luck,
>
> T G-R

Re: /dev/bcache/by-uuid directory empty

[Nathan Dehnel]

(define-module (gooby-channel packages bcache-tools)
  #:use-module (guix licenses)
  #:use-module (guix packages)
  #:use-module (gnu packages)
  #:use-module (guix build-system gnu)
  #:use-module (guix git-download)
  #:use-module (gnu packages linux)
  #:use-module (gnu packages pkg-config))

(define-public bcache-tools
  (package
    (name "bcache-tools")
    (version "1.1")
    (source
     (origin
       (method git-fetch)
       (uri
        (git-reference
         (url (string-append
"https://git.kernel.org/pub/scm/linux/kernel/git/colyli/" name
".git"))
         (commit (string-append name "-" version))))
       (file-name (git-file-name name version))
       (sha256
        (base32
         "1vfqm3asx7h1sjwyq45dki4wk7lkipqrx2pw2hnqm4xir85qf67h"))
       (patches (search-patches "bcache-tools-noprobe.patch"))))
    (build-system gnu-build-system)
    (arguments
     `(;;#:tests? #f                      ; no "check" target
       #:make-flags
         (list (string-append "PREFIX=" (assoc-ref %outputs "out")))
       #:phases
         (modify-phases %standard-phases
          (delete 'configure))))
    (inputs
     `(("util-linux" ,util-linux)))
    (native-inputs
     `(("pkg-config" ,pkg-config)))
    (home-page "https://bcache.evilpiepirate.org/")
    (synopsis "These are the userspace tools required for bcache.")
    (description "Bcache patches for the Linux kernel allow one to use
SSDs to cache other block devices. It's analogous to L2Arc for ZFS,
but Bcache also does writeback caching (besides just write through
caching), and it's filesystem agnostic. ")
    (license gpl2)))

I tried to make a package, but I got stuck.
https://www.mail-archive.com/bug-guix@gnu.org/msg00180.html
According to this,  if you use gnu-build-system, all packages added to
inputs get added to PKG_CONFIG_PATH, but for some reason it's not
happening for util-linux, which causes a build error.

On Fri, Dec 18, 2020 at 10:31 AM Nathan Dehnel <ncdehnel@gmail.com> wrote:
>
> >which is a bit more than that.  Guix doesn't ship bcache-tools
> (yet); are you using your own package?  If so, please consider
> sharing :-)
>
> I could try to make a package.
>
> >Have you tried this?
>
> Yes.
>
> On Fri, Dec 18, 2020 at 8:13 AM Tobias Geerinckx-Rice <me@tobias.gr> wrote:
> >
> > Nathan,
> >
> > You may well be the first to (try to) use bcache on Guix System.
> >
> > Nathan Dehnel 写道：
> > > The manual https://www.kernel.org/doc/Documentation/bcache.txt
> > > states
> > > that udev is necessary, and it is enabled:
> >
> > It says:
> >
> > --8<---------------cut here---------------start------------->8---
> > bcache-tools now ships udev rules, and bcache devices are known to
> > the kernel immediately.
> > --8<---------------cut here---------------end--------------->8---
> >
> > which is a bit more than that.  Guix doesn't ship bcache-tools
> > (yet); are you using your own package?  If so, please consider
> > sharing :-)
> >
> > You'd have to add it to the RULES field of your system's
> > UDEV-CONFIGURATION to make the system's udev ‘see’ the rules.
> > Simply installing it or adding it to your system packages isn't
> > enough.
> >
> > The kernel docs continue:
> >
> > --8<---------------cut here---------------start------------->8---
> > Without udev, you can manually register devices like this::
> >
> >   echo /dev/sdb > /sys/fs/bcache/register
> >   echo /dev/sdc > /sys/fs/bcache/register
> >
> > Registering the backing device makes the bcache device show up in
> > /dev; you can now format it and use it as normal.
> > --8<---------------cut here---------------end--------------->8---
> >
> > Have you tried this?
> >
> > Good luck,
> >
> > T G-R