[Buildroot] [PATCH 1/1] manual/faq: add section about why no binary packages
Danomi Manchego
danomimanchego123 at gmail.com
Mon Feb 17 20:21:40 UTC 2014
Yann,
Nit-picky writing editorial - no issue with the actual content ...
On Mon, Feb 17, 2014 at 12:52 PM, Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
> From: "Yann E. MORIN" <yann.morin.1998 at free.fr>
>
> It comes up every now and then on the list, so better be prepared to
> point at the manual, rather than rehash the same every time.
>
> Most of the chapter is a copy-paste of the report from the Buildroot
> Developpers Day in Pragues, 2011-10-28:
> http://lists.busybox.net/pipermail/buildroot/2011-November/047229.html
>
> We consider the opinions expressed in that report to be still valid
> now, two years later.
>
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
> Cc: Samuel Martin <s.martin49 at gmail.com>
> Cc: Peter Korsgaard <jacmet at uclibc.org>
> Cc: Arnout Vandecappelle <arnout at mind.be>
> Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Cc: Thomas De Schampheleire <patrickdepinguin at gmail.com>
> Cc: Baruch Siach <baruch at tkos.co.il>
> ---
> docs/manual/faq-troubleshooting.txt | 91 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 91 insertions(+)
>
> diff --git a/docs/manual/faq-troubleshooting.txt b/docs/manual/faq-troubleshooting.txt
> index 4e0612b..636b3b6 100644
> --- a/docs/manual/faq-troubleshooting.txt
> +++ b/docs/manual/faq-troubleshooting.txt
> @@ -111,3 +111,94 @@ directory as the new root, will most likely fail.
> If you want to run the target filesystem inside a chroot, or as an NFS
> root, then use the tarball image generated in +images/+ and extract it
> as root.
> +
> +[[faq-no-binary-packages]]
> +Why doesn't Buildroot generate binary packages (.deb, .ipkg...)?
> +----------------------------------------------------------------
> +
> +One feature that is often discussed on the Buildroot list, is the
no comma
> +the general topic of "package management". To summarize, the idea
> +would be to add some tracking of which Buildroot package installs
> +what files, with the goals of:
> +
> + * Being able to remove files installed by a package when this package
> + gets unselected from the menuconfig ;
; -> .
> +
> + * Ultimately, be able to generate binary packages (ipk or other
> + format) that can be installed on the target without re-generating a
> + new root filesystem image.
There's some tense inconsistency here between the first point ("Being
able to...") and the second ("be able to...")
> +
> +In general, most people think it is easy to do: just track which package
> +installed what and remove it when the package is unselected. However, it
> +is much more complicated than that:
> +
> + * It is not only about the +target/+ directory, but also the sysroot in
> + +host/usr/<tuple>/sysroot+ and the +host/+ directory itself. All files
> + installed in those directories by various packages must be tracked.
> +
> + * When a package is removed, it is not sufficient to remove just the
> + files it installed. One must also remove all its reverse
> + dependencies (i.e packages relying on it) and rebuild all those
> + packages. For example, package A depends optionally on the OpenSSL
> + library. Both are selected, and Buildroot is built. Package A is
> + built with crypto support using OpenSSL. Later on, OpenSSL gets
> + unselected from the configuration, but package A remains (since
remains (since ,,, possible). -> remains. (Since ... possible.)
> + OpenSSL is an optional dependency, this is possible). If you just
> + remove the OpenSSL files, then the files installed by package A are
> + broken: they use a library that is no longer present on the
> + target. Technically, it is possible to do this (the prototype that
> + Lionel Landwerlin and Thomas Petazzoni have worked on started to do
> + this), but it is difficult and adds a fair bit of complexity.
"a fair bit of" may be colloquial. Maybe change to "a lot of"?
> +
> + * In addition to the previous problem, there is the case where the
> + optional dependency is not even known to Buildroot. For example,
> + package A in version 1.0 never used OpenSSL, but in version 2.0 it
> + automatically uses OpenSSL if available. If the Buildroot .mk file
> + hasn't been updated to take this into account, then package A will
> + not be part of the reverse dependencies of OpenSSL and will not be
> + removed and rebuilt when OpenSSL is removed. For sure, the .mk file
> + of package A should be fixed to mention this optional dependency,
> + but in the mean time, you can have non-reproducible behaviors.
> +
> + * The whole idea is also to allow changes in the menuconfig to be
Too conversational: "whole idea". Maybe "idea" or "implied goal"?
> + applied on the output directory without having to rebuild
> + everything from scratch. However, this is very difficult to achieve
> + in a reliable way: what happens when the suboptions of a package
> + are changed (we would have to detect this, and rebuild the package
> + from scratch and potentially all its reverse dependencies), what
> + happens if toolchain options are changed, etc. At the moment, what
> + Buildroot does is clear and simple so its behaviour is very
> + reliable and it is easy to support users. If we start telling users
> + that the configuration changes done in menuconfig are applied after
"If we start telling users that" may be too conversational. Maybe "If
we claim that"?
> + the next make, then it has to work correctly and properly in all
> + situations, and not have some bizarre corner cases. We fear bug
> + reports like "I have enabled package A, B and C, then ran make,
> + then disabled package C and enabled package D and ran make, then
> + re-enabled package C and enabled package E and then there is a
> + build failure". Or worse "I did some configuration, then built,
> + then did some changes, built, some more changes, built, some more
> + changes, built, and now it fails, but I don't remember all the
> + changes I did and in which order". This will be impossible to
> + support.
> +
> +For all these reasons, the conclusion is that adding tracking of
> +installed files to remove them when the package is unselected, or to
> +generate a repository of binary packages, is something that is very
> +hard to achieve reliably and will add a lot of complexity.
> +
> +On this matter, the Buildroot developpers make these position statements:
developpers -> developers
> +
> + * Buildroot strives at making it easy to generate a root filesystem
strives at making -> strives to make
> + (hence the name, by the way). That is what we want to make Buildroot
> + good at: building root filesystems.
> +
> + * Buildroot is not meant to be a distribution (or rather, a distribution
> + generator). It is the opinion of most Buildroot developers that this
> + is not a goal we should pursue. We believe that there are other tools
> + better suited to generate a distro than Buildroot is. For example,
than Buildroot is. -> than Buildroot.
Danomi -
> + http://openembedded.org/[Open Embedded], or https://openwrt.org/[openWRT],
> + are such tools.
> +
> + * We prefer to push Buildroot in a direction that makes it easy (or even
> + easier) to generate complete root filesystems. This is what makes
> + Buildroot stands out in the crowd (among other things, of course!).
> --
> 1.8.1.2
>
> _______________________________________________
> buildroot mailing list
> buildroot at busybox.net
> http://lists.busybox.net/mailman/listinfo/buildroot
More information about the buildroot
mailing list