[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Hello,

At ELCE, I will be talking about "Using Buildroot for real projects".
You can see my talk summary at
https://events.linuxfoundation.org/events/embedded-linux-conference-europe/petazzoni.

The current (unfinished) status of my slides is visible at:
  http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf

The goal of the talk is to give some recommendations and best practices
on how to use Buildroot. As I'm sure I forgot a lot of things in my
slides above, I'd like to know what you, Buildroot developers/users,
would have to say on the topic, so that I can improve the contents of
this presentation.

Regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Peter Korsgaard]

>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@free-electrons.com> writes:

 Thomas> Hello,
 Thomas> At ELCE, I will be talking about "Using Buildroot for real projects".
 Thomas> You can see my talk summary at
 Thomas> https://events.linuxfoundation.org/events/embedded-linux-conference-europe/petazzoni.

 Thomas> The current (unfinished) status of my slides is visible at:
 Thomas>   http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf

Thanks, a few quick comments:

p3: s/How it works?/How does it work?/
p5: minor, configuration doesn't match output on p6
p7: "It does not track which packages installs what" <- Is that
    important to know how it works?
p9: use uclibc and rootfs size would be half ;)
p11: s/needs to build rebuilt/needs to be rebuilt/
p11: s/built with crosstool-NG/from above/
p12: s/knows some/contains presets for/
p12: s/well-known toolchains/well-known binary toolchains/
p14: s/for it build/for it to build/
p16: "Up to Buildroot 2011.11" reads a bit odd to me (E.G. is it now
     fixed or not?) Perhaps simply say "Until recently, it wasn't easy
     to use Buildroot with a custom"

-- 
Bye, Peter Korsgaard

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Baruch Siach]

Hi Thomas,

On Mon, Oct 17, 2011 at 06:47:18PM +0200, Thomas Petazzoni wrote:
> At ELCE, I will be talking about "Using Buildroot for real projects".
> You can see my talk summary at
> https://events.linuxfoundation.org/events/embedded-linux-conference-europe/petazzoni.
> 
> The current (unfinished) status of my slides is visible at:
>   http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
> 
> The goal of the talk is to give some recommendations and best practices
> on how to use Buildroot. As I'm sure I forgot a lot of things in my
> slides above, I'd like to know what you, Buildroot developers/users,
> would have to say on the topic, so that I can improve the contents of
> this presentation.

A few comments.

1. Slide 7: maybe elaborate a bit on the meaning of "It does not track which 
   package installs what", i.e. you can't uninstall (or install) a package 
   form the target.

2. Slide 14 header: maybe "External toolchains: HOWTO"

3. Slide 19: the sysroot copying stage seems to be missing

4. Slide 22: the 'echo' command is missing '-e'?

5. Slides 23-26: headers should be "... (x/5)"

6. Slide 27: old style CMAKETARGETS

By the way, is there a link to the TeX (or DocBook?) source of this 
presentation.  I'd really like to learn a few Beamer tricks, like the source 
box in slides 17, 18.

baurch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Tue, 18 Oct 2011 09:26:38 +0200,
Baruch Siach <baruch@tkos.co.il> a ?crit :

> By the way, is there a link to the TeX (or DocBook?) source of this 
> presentation.  I'd really like to learn a few Beamer tricks, like the
> source box in slides 17, 18.

It's just

\begin{block}{}
\small
\begin{verbatim}
Some code here.
\end{verbatim}
\end{block}

I've attached the .tex source for reference, however it won't build
since it depends on a Free Electrons stylesheet (but I can share it as
well if you need). Some day, we'll have an publicly accessible Git
repository for all our training materials and conference slides.

Thanks for your comments!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas De Schampheleire]

Hi Thomas,

On Mon, Oct 17, 2011 at 6:47 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Hello,
>
> At ELCE, I will be talking about "Using Buildroot for real projects".
> You can see my talk summary at
> https://events.linuxfoundation.org/events/embedded-linux-conference-europe/petazzoni.
>
> The current (unfinished) status of my slides is visible at:
> ?http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
>
> The goal of the talk is to give some recommendations and best practices
> on how to use Buildroot. As I'm sure I forgot a lot of things in my
> slides above, I'd like to know what you, Buildroot developers/users,
> would have to say on the topic, so that I can improve the contents of
> this presentation.


First of all, I think it is a very interesting presentation. It should
definitely become part of the official buildroot documentation, so
that companies starting with buildroot get a better feeling about the
best practices.

Some typos and comments, in addition to the previous replies:

p2 s/intagration/integration/
p3 s/Example of systems/Examples of systems/
p3 s/Toolchain recommandations/Toolchain recommendations/
p7 s/in a .config files/in a .config file/
p7 s/starts by/starts with/
p8 s/What does it generates/What does it generate/
p11 s/CodeSoucery/CodeSourcery/
p15 s/recommandation/recommendation/
p16 s/Kernel and bootloaders changes/Kernel and bootloader changes/
p16 s/separatly/separately/
p16 close parentheses after BR2_LINUX_KERNEL_PATCH



p 11: "Buildroot builds a toolchain. This is limited to uClibc based
toolchains, and needs to build rebuilt completely at every
Buildroot rebuild."
I think this is confusing: to me it gives the impression that the
toolchain is rebuilt at every invocation of 'make'. Maybe adding the
word 'complete' as with crosstool-ng makes it more clear.

p 14: "Generate a custom toolchain, and store it pre-built next to the
Buildroot directory, or in some internal HTTP server"
It could be anywhere on the filesystem, plus doesn't buildroot support
FTP either? Moreover, patches are coming to add scp support as well.
My point is that mentioning 'http' explicitly is maybe too
restrictive.

p27: It's a pity that the dependencies don't fit completely in the
box. Maybe use MY_APP instead of MY_APPLICATION or something?

p28: "storage in configs/": I think it would be better to explicitly
mention that the file 'defconfig' should be stored in configs/

p30: Future: would you consider mentioning that support for Mercurial
repositories and 'scp' downloads for LAN-based locations is in queue?


As I side note : I read that you use /rootfs-additions/ to add
additional stuff in the root filesystem. I'm doing exactly the same
thing (called target_skeleton_extras). I feel this may be a good thing
to officialize: let the user specify an overlay to the target
skeleton. What do you think? (we may want to discuss this in a
separate topic)


Good luck with the presentation!
Thomas

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Arnout Vandecappelle]

On Monday 17 October 2011 18:47:18, Thomas Petazzoni wrote:
> The goal of the talk is to give some recommendations and best practices
> on how to use Buildroot. As I'm sure I forgot a lot of things in my
> slides above, I'd like to know what you, Buildroot developers/users,
> would have to say on the topic, so that I can improve the contents of
> this presentation.

 Of course, I can't stay behind with giving my comments!  They're a bit
broader than the earlier comments, though.

 For the 'What is Buildroot slide', I would split it in a 'What' and a 'Why' slide (bottom/top half).  Also, the goal for me is to build a complete Linux-based embedded system with the minimum amount of hassle.  That means:
 - minimal dependency on the build host's operating system (no specific bitbake or whatever package needs to be installed);
 - reproducible builds;
 - builds everything.

 About the "Buildroot can import external toolchains": it's not the option that I would advise at this time.  A major disadvantage is that there may be inconsistencies between what buildroot thinks the toolchain can do and what it actually can (unless it's a CodeSourcery toolchain, but those use glibc) - you have to define yourself what extra stuff the toolchain has.

 The board/<company>/<project>/linux-patches setup is exactly what I typically use as well.  I would like some future version of buildroot to simplify such a setup, i.e. you just configure board/<company>/<project> and buildroot looks for all the patches there.  But that's not for this presentation :-)

 One typical use case that is missing: in a company with several developers, you would put a download mirror in some central location and either point 
BR2_DL_DIR or BR2_PRIMARY_SITE to it.  (BTW, now I notice that the help text of BR2_PRIMARY_SITE incorrectly claims that it only works for AUTOTARGETS.)

 Another important hint: to debug, you should use output/host/usr/bin/<arch>-gdb -ex 'set solib-absolute-prefix output/staging'.

 And it may be worthwhile to talk about how you can contribute :-)  DCO, coding style, where to send it.


 Regards,
 Arnout

-- 
Arnout Vandecappelle                               arnout at mind be
Senior Embedded Software Architect                 +32-16-286540
Essensium/Mind                                     http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium                BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  31BB CF53 8660 6F88 345D  54CC A836 5879 20D7 CF43

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas De Schampheleire]

Hi Arnout,

On Tue, Oct 18, 2011 at 11:35 PM, Arnout Vandecappelle <arnout@mind.be> wrote:
>
> On Monday 17 October 2011 18:47:18, Thomas Petazzoni wrote:
>> The goal of the talk is to give some recommendations and best practices
>> on how to use Buildroot. As I'm sure I forgot a lot of things in my
>> slides above, I'd like to know what you, Buildroot developers/users,
>> would have to say on the topic, so that I can improve the contents of
>> this presentation.
>
> ?Of course, I can't stay behind with giving my comments! ?They're a bit
> broader than the earlier comments, though.
>
> ?For the 'What is Buildroot slide', I would split it in a 'What' and a 'Why' slide (bottom/top half). ?Also, the goal for me is to build a complete Linux-based embedded system with the minimum amount of hassle. ?That means:
> ?- minimal dependency on the build host's operating system (no specific bitbake or whatever package needs to be installed);
> ?- reproducible builds;
> ?- builds everything.
>
> ?About the "Buildroot can import external toolchains": it's not the option that I would advise at this time. ?A major disadvantage is that there may be inconsistencies between what buildroot thinks the toolchain can do and what it actually can (unless it's a CodeSourcery toolchain, but those use glibc) - you have to define yourself what extra stuff the toolchain has.
>
> ?The board/<company>/<project>/linux-patches setup is exactly what I typically use as well. ?I would like some future version of buildroot to simplify such a setup, i.e. you just configure board/<company>/<project> and buildroot looks for all the patches there. ?But that's not for this presentation :-)
>
> ?One typical use case that is missing: in a company with several developers, you would put a download mirror in some central location and either point
> BR2_DL_DIR or BR2_PRIMARY_SITE to it. ?(BTW, now I notice that the help text of BR2_PRIMARY_SITE incorrectly claims that it only works for AUTOTARGETS.)

I noticed this as well. I fixed this in my hg/scp support patch that I
will send shortly.

>
> ?Another important hint: to debug, you should use output/host/usr/bin/<arch>-gdb -ex 'set solib-absolute-prefix output/staging'.

Is this really needed?
I'm under the impression that setting sysroot is enough: 'set sysroot
output/staging'

>
> ?And it may be worthwhile to talk about how you can contribute :-) ?DCO, coding style, where to send it.

Best regards,
Thomas

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Mon, 17 Oct 2011 18:47:18 +0200,
Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a ?crit :

> The current (unfinished) status of my slides is visible at:
>   http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf

First of all, I'd like to thank Peter, Baruch, Thomas, Arnout and Will
who gave some useful comments about my slides.

At the same URL above, I have published a new version, which hopefully
addresses your comments, and also adds some more slides on various
topics. The slides should now, at least in terms of contents, represent
what I had in mind for this talk.

Now, if you're still willing to spend some time on this, I'd like to
have comments on:
 * remaining english typos, wording improvements, etc.
 * suggestions of additional contents/topics if there is something I
   missed. Like if you use best practices that aren't described in
   those slides.

Thanks again!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Yegor Yefremov]

On Fri, Oct 21, 2011 at 3:43 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Le Mon, 17 Oct 2011 18:47:18 +0200,
> Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a ?crit :
>
>> The current (unfinished) status of my slides is visible at:
>> ? http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
>
> First of all, I'd like to thank Peter, Baruch, Thomas, Arnout and Will
> who gave some useful comments about my slides.
>
> At the same URL above, I have published a new version, which hopefully
> addresses your comments, and also adds some more slides on various
> topics. The slides should now, at least in terms of contents, represent
> what I had in mind for this talk.
>
> Now, if you're still willing to spend some time on this, I'd like to
> have comments on:
> ?* remaining english typos, wording improvements, etc.
> ?* suggestions of additional contents/topics if there is something I
> ? missed. Like if you use best practices that aren't described in
> ? those slides.

thanks for sharing this slides. I found some really useful issues I
have never thought about before.

Page 23 (setting root password):

1. what have you set?
2. $TARGET_DIR is not working for me, but $1/etc/shadow is working

Yegor

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Fri, 21 Oct 2011 15:51:51 +0200,
Yegor Yefremov <yegorslists@googlemail.com> a ?crit :

> thanks for sharing this slides. I found some really useful issues I
> have never thought about before.

You're welcome. Nice to see it is useful.

> Page 23 (setting root password):
> 
> 1. what have you set?

The root password.

> 2. $TARGET_DIR is not working for me, but $1/etc/shadow is working

Fixed. I usually do TARGETDIR=$1 or TARGET_DIR=$1 at the beginning of
the script.

Thanks for the review!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Yegor Yefremov]

>> Page 23 (setting root password):
>>
>> 1. what have you set?
>
> The root password.

What is root password: 'root', 'linux' or something else? I tried
both, but failed. I mean, if someone tries to copy this line, he won't
be able to login.

Perhaps some howto about how to generate own root password and put it
in the script could be also useful. On the other hand it could be
included in the main documentation later.

Yegor

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Fri, 21 Oct 2011 16:24:03 +0200,
Yegor Yefremov <yegorslists@googlemail.com> a ?crit :

> What is root password: 'root', 'linux' or something else? I tried
> both, but failed. I mean, if someone tries to copy this line, he won't
> be able to login.

Ah, my mistake, I copy pasted the hashed password from a project, and
the password is not 'root'. I've fixed that in the slides, will be part
of the next version I'll upload.

> Perhaps some howto about how to generate own root password and put it
> in the script could be also useful. On the other hand it could be
> included in the main documentation later.

Just use mkpasswd from the whois package in Debian/Ubuntu distributions.

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Will Wagner]

On 21/10/2011 14:43, Thomas Petazzoni wrote:
> Le Mon, 17 Oct 2011 18:47:18 +0200,
> Thomas Petazzoni<thomas.petazzoni@free-electrons.com>  a ?crit :
>
>> The current (unfinished) status of my slides is visible at:
>>    http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
<snip>
> Now, if you're still willing to spend some time on this, I'd like to
> have comments on:
>   * remaining english typos, wording improvements, etc.

Couple of minor points on the English (Still very impressive from a non 
native speaker)
p8: "Buildroot starts by the toolchain" should be "starts with the"
p16 "Any other project specific file" should perhaps be "files"
p17: "kernel and bootloaders often" shouldn't it be singular bootloader?
p17: "drawback is that Buildroot does directly" unless I misunderstand 
the use case, don't you mean doesn't?
p21: "I don't recommend this, ..." I'm not sure if you are not 
recommending changing the skeleton or using a script to modify it
p30: "finds automagically" should be "automagically finds"
p37: "assignements" should be assignments
p37: "allows to tell" should be "allows you to tell"

>   * suggestions of additional contents/topics if there is something I
>     missed. Like if you use best practices that aren't described in
>     those slides.

One thing I'd love to get written up somewhere is best practice for NFS 
mounting a filesystem image, but I realise this may not be relevant to 
your talk.

Otherwise your slides are very good at explaining how it all works.

Will

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Fri, 21 Oct 2011 15:33:30 +0100,
Will Wagner <will_wagner@carallon.com> a ?crit :

> Couple of minor points on the English (Still very impressive from a
> non native speaker)

Thanks!

> p8: "Buildroot starts by the toolchain" should be "starts with the"

Funny, because Will Moore told me to do the exact opposite (in a review
he sent me privately yesterday):

"""
Slide 7, "Buildroot starts with the toolchain" not "Buildroot starts by
the toolchain".
"""

Now I understand why I fail to further improve my english. It's because
it's a fuzzy logic language ! :-)

> p16 "Any other project specific file" should perhaps be "files"

I have changed to "All other project specific files", maybe it's more
correct?

> p17: "kernel and bootloaders often" shouldn't it be singular
> bootloader?

Not necessarily. On AT91 platforms, you have two bootloaders:
at91boostrap and u-boot, and I both patch them and build them within
Buildroot.

> p17: "drawback is that Buildroot does directly" unless I
> misunderstand the use case, don't you mean doesn't?

Fixed, thanks, that was a major typo.

> p21: "I don't recommend this, ..." I'm not sure if you are not 
> recommending changing the skeleton or using a script to modify it

Ok, I tried to clarify it:

"""I don't recommend this solution as it consists in duplicating the
default skeleton, which would prevent from taking advantage of future
improvements of the default skeleton."""

> p30: "finds automagically" should be "automagically finds"

Fixed.

> p37: "assignements" should be assignments

Fixed.

> p37: "allows to tell" should be "allows you to tell"

Fixed.
 
> One thing I'd love to get written up somewhere is best practice for
> NFS mounting a filesystem image, but I realise this may not be
> relevant to your talk.

Ah, good point. I'll include a slide about this.

Thanks!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas De Schampheleire]

Hi Thomas,

On Fri, Oct 21, 2011 at 3:43 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Le Mon, 17 Oct 2011 18:47:18 +0200,
> Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a ?crit :
>
>> The current (unfinished) status of my slides is visible at:
>> ? http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
>
> First of all, I'd like to thank Peter, Baruch, Thomas, Arnout and Will
> who gave some useful comments about my slides.
>
> At the same URL above, I have published a new version, which hopefully
> addresses your comments, and also adds some more slides on various
> topics. The slides should now, at least in terms of contents, represent
> what I had in mind for this talk.
>
> Now, if you're still willing to spend some time on this, I'd like to
> have comments on:
> ?* remaining english typos, wording improvements, etc.
> ?* suggestions of additional contents/topics if there is something I
> ? missed. Like if you use best practices that aren't described in
> ? those slides.

p4: s/build a kernel image/a kernel image/   (the 'build' is already
mentioned in the header)
p4: for symmetry reasons, I would suggest to start the last point also
with 'It builds' instead of 'Builds'
p4: the 'composed of Busybox' seems odd to me, because 'Busybox' is
one item. Maybe a native English speaker (Will?) can give feedback on
this. Suggestions from me are 'containing Busybox' or 'based on
Busybox'.

p4/5 title: on page 4 there is a question mark, not so on page 5.

p5: I'm unsure what you're trying to say with 'Standard languages
used'. If you refer to make, that was already covered on the previous
slide and may be redundant here.

p5: you're mainly typing full sentences, which is good IMO. But the
'Need to do complete rebuilds' is not consistent with that. I'd
suggest 'You need to ...'.

p10/11: reminder: still lists a TODO about build time

p12: s/more choice/more choices/    (at least, that's my feeling)
p12: first bullet says: "Buildroot complete rebuild", second says:
"complete Buildroot rebuild". This should be consistent. I prefer the
second one.

p24: s/Creating/Create/
p31: s/Mouting/Mounting/



Thanks for the credit, and:
Great job!

Best regards,
Thomas

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Baruch Siach]

Hi Thomas,

On Fri, Oct 21, 2011 at 03:43:03PM +0200, Thomas Petazzoni wrote:
> Le Mon, 17 Oct 2011 18:47:18 +0200,
> Thomas Petazzoni <thomas.petazzoni@free-electrons.com> a ?crit :
> 
> > The current (unfinished) status of my slides is visible at:
> >   http://free-electrons.com/~thomas/pub/using-buildroot-real-project.pdf
> 
> First of all, I'd like to thank Peter, Baruch, Thomas, Arnout and Will
> who gave some useful comments about my slides.
> 
> At the same URL above, I have published a new version, which hopefully
> addresses your comments, and also adds some more slides on various
> topics. The slides should now, at least in terms of contents, represent
> what I had in mind for this talk.
> 
> Now, if you're still willing to spend some time on this, I'd like to
> have comments on:
>  * remaining english typos, wording improvements, etc.
>  * suggestions of additional contents/topics if there is something I
>    missed. Like if you use best practices that aren't described in
>    those slides.
> 
> Thanks again!

Two of my earlier comments still stand.

1. Slide 23: missing -e in the 'echo' command

$ echo "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0

$ echo -e "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
/dev/mtdblock7      /applog jffs2   defaults        0   0

2. Slides 24-27: header should be "Project-specific packages (x/5)", instead 
   of "... (x/4)".  (Can't TeX do this automatically somehow?)

baruch

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch at tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Sun, 23 Oct 2011 14:37:55 +0200,
Baruch Siach <baruch@tkos.co.il> a ?crit :

> 1. Slide 23: missing -e in the 'echo' command
> 
> $ echo "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
> /dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0
> 
> $ echo -e "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
> /dev/mtdblock7      /applog jffs2   defaults        0   0

-e is not needed with sh:

$ echo "bla\nbli"
bla
bli
$ echo -e "bla\nbli"
-e bla
bli

> 2. Slides 24-27: header should be "Project-specific packages (x/5)", instead 
>    of "... (x/4)".  (Can't TeX do this automatically somehow?)

Fixed. I don't know if TeX can do this automatically. Maybe.

Thanks for the comments. I also fixed the various comments raised by
Thomas. Thanks again!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Yann E. MORIN]

Thomas, All,

On Monday 24 October 2011 17:32:50 Thomas Petazzoni wrote:
> Le Sun, 23 Oct 2011 14:37:55 +0200,
> Baruch Siach <baruch@tkos.co.il> a ?crit :
> 
> > 1. Slide 23: missing -e in the 'echo' command
> > 
> > $ echo "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
> > /dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0
> > 
> > $ echo -e "/dev/mtdblock7\t\t/applog\tjffs2\tdefaults\t\t0\t0"
> > /dev/mtdblock7      /applog jffs2   defaults        0   0
> 
> -e is not needed with sh:

The problem is that /bin/sh might be whatever. With a POSIX-conformant
/bin/sh (eg. dash), this is true. With bash, it is not. Alas, many
systems still have bash as /bin/sh.

$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 May 17 23:53 /bin/sh -> bash
$ echo "bli\nbla"
bli\nbla
$ /bin/bash
$ echo "bli\nbla"
bli\nbla
$ exit
$ /bin/dash
$ echo "bli\nbla"
bli
bla

The answer it to use printf [0].

I now use printf as much as I can. printf is in POSIX and does not suffer
from all the discrepancies there are in the many echo implementations.

> $ echo "bla\nbli"
> bla
> bli
> $ echo -e "bla\nbli"
> -e bla
> bli

[0] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/printf.html

Regards,
Yann E. MORIN.

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[Buildroot] [RFC] Slides "Using Buildroot for real projects"

[Thomas Petazzoni]

Le Mon, 24 Oct 2011 18:42:06 +0200,
"Yann E. MORIN" <yann.morin.1998@anciens.enib.fr> a ?crit :

> The problem is that /bin/sh might be whatever. With a POSIX-conformant
> /bin/sh (eg. dash), this is true. With bash, it is not. Alas, many
> systems still have bash as /bin/sh.
> 
> $ ls -l /bin/sh
> lrwxrwxrwx 1 root root 4 May 17 23:53 /bin/sh -> bash
> $ echo "bli\nbla"
> bli\nbla
> $ /bin/bash
> $ echo "bli\nbla"
> bli\nbla
> $ exit
> $ /bin/dash
> $ echo "bli\nbla"
> bli
> bla
> 
> The answer it to use printf [0].
> 
> I now use printf as much as I can. printf is in POSIX and does not suffer
> from all the discrepancies there are in the many echo implementations.

Ah, nice to know. Thanks!

For the moment, I've been using echo, knowing that its behavior is not
consistent across systems. But indeed printf is much better.

Thanks!

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com