From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "Jürgen Groß" <jgross@suse.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"Wei Liu" <wl@xen.org>, "Ian Jackson" <ian.jackson@eu.citrix.com>,
"George Dunlap" <George.Dunlap@citrix.com>
Subject: Re: Getting rid of (many) dynamic link creations in the xen build
Date: Fri, 16 Oct 2020 08:52:42 +0200 [thread overview]
Message-ID: <efb22794-7573-3fe8-516e-8f7a817341af@suse.com> (raw)
In-Reply-To: <ad909278-8ab0-dc7a-2004-5efd08e5acbd@citrix.com>
On 15.10.2020 22:52, Andrew Cooper wrote:
> On 15/10/2020 11:41, Jürgen Groß wrote:
>> On 15.10.20 12:09, Jan Beulich wrote:
>>> On 15.10.2020 09:58, Jürgen Groß wrote:
>>>> After a short discussion on IRC yesterday I promised to send a mail
>>>> how I think we could get rid of creating dynamic links especially
>>>> for header files in the Xen build process.
>>>>
>>>> This will require some restructuring, the amount will depend on the
>>>> selected way to proceed:
>>>>
>>>> - avoid links completely, requires more restructuring
>>>> - avoid only dynamically created links, i.e. allowing some static
>>>> links which are committed to git
>>>
>>> While I like the latter better, I'd like to point out that not all
>>> file systems support symlinks, and hence the repo then couldn't be
>>> stored on (or the tarball expanded onto) such a file system. Note
>>> that this may be just for viewing purposes - I do this typically at
>>> home -, i.e. there's no resulting limitation from the build process
>>> needing symlinks. Similarly, once we fully support out of tree
>>> builds, there wouldn't be any restriction from this as long as just
>>> the build tree is placed on a capable file system.
>>>
>>> As a result I'd like to propose variant 2´: Reduce the number of
>>> dynamically created symlinks to a minimum. This said, I have to
>>> admit that I haven't really understood yet why symlinks are bad.
>>> They exist for exactly such purposes, I would think.
>>
>> Not the symlinks as such, but the dynamically created ones seem to be
>> a problem, as we stumble upon those again and again.
>
> We have multiple build system bugs every release to do with dynamically
> generated symlinks. Given that symlinks aren't a hard requirement, this
> is a massive price to pay, and time which could be better spent doing
> other other things.
>
> Also, they prohibit the ability to build from a read-only source dir.
In which way? In an out-of-tree build (see Linux) this gets created
in the build tree, not the source one. Or else ...
> The asm symlink in particular prevents any attempt to do concurrent
> builds of xen. In some future, I'd love to be able to do concurrent
> out-of-tree builds of Xen on different architectures, because elapsed
> time to do this is one limiting factor of mine on pre-push sanity checks.
... this wouldn't already be possible there (including varying arch-es
built from the same source tree).
Jan
next prev parent reply other threads:[~2020-10-16 6:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 7:58 Getting rid of (many) dynamic link creations in the xen build Jürgen Groß
2020-10-15 10:09 ` Jan Beulich
2020-10-15 10:41 ` Jürgen Groß
2020-10-15 20:52 ` Andrew Cooper
2020-10-16 6:52 ` Jan Beulich [this message]
2020-10-16 6:58 ` Jan Beulich
2020-10-16 7:25 ` Jürgen Groß
2020-10-16 8:11 ` Jan Beulich
2020-10-15 10:49 ` Jürgen Groß
2020-10-16 6:59 ` Jan Beulich
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