Re: [Buildroot] how to get buildroot to update a git repo that has changes? (ie building HEAD vs a specific SHA)

From: Baruch Siach via buildroot <buildroot@buildroot.org>
To: Tim Harvey <tharvey@gateworks.com>
Cc: buildroot <buildroot@buildroot.org>
Subject: Re: [Buildroot] how to get buildroot to update a git repo that has changes? (ie building HEAD vs a specific SHA)
Date: Sat, 07 May 2022 23:05:52 +0300	[thread overview]
Message-ID: <8735hl9kdt.fsf@tarshish> (raw)
In-Reply-To: <CAJ+vNU3KHR+J0y9o3CVOC+1zA6G3=kQG2G_bQ2PSegFho8c9BA@mail.gmail.com>

Hi Tim,

On Fri, May 06 2022, Tim Harvey wrote:
> On Thu, May 5, 2022 at 8:21 PM Baruch Siach <baruch@tkos.co.il> wrote:
>> On Thu, May 05 2022, Tim Harvey wrote:
>> > Greetings,
>> >
>> > I use buildroot to build a Linux kernel+ramdisk using:
>> > BR2_LINUX_KERNEL_CUSTOM_GIT=y
>> > BR2_LINUX_KERNEL_CUSTOM_REPO_URL=<gitrepo>
>> > BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION=<gitbranch>
>> >
>> > When the upstream branch changes I would like to build that kernel but
>> > I find that buildroot caches the repo in dl/linux/.git and doesn't
>> > seem to know how to check to see if there are new commits.
>> >
>> > I realize that this is atypical as typically you want to configure
>> > buildroot for a specific package gitsha/tag.
>> >
>> > How would I go about getting buildroot to update the repo? I don't
>> > particularly want to rm dl/linux I want to instead somehow check to
>> > see if the repo needs a refresh then refresh it without a massive
>> > network download.
>>
>> Using a branch name for _VERSION is not supported. See the rationale in
>> the manual section 18.6.2, note on LIBFOO_VERSION description.
>>
>>   https://buildroot.org/downloads/manual/manual.html
>>
>> You might want to consider using OVERRIDE_SRCDIR to make Buildroot build
>> your local kernel source tree. See section 8.14.6 in the manual.
>
> Thanks for the references. I do understand that it is not supported. I
> guess I was looking for a few simple lines of shell that would tell me
> if the cached repo was out of date so that I could remove it.
> # get branch from BR2 config
> KERNEL_BRANCH=$(grep BR2_LINUX_KERNEL_CUSTOM_REPO_VERSION .config |
> cut -d= -f2 | tr -d \")
> # get the HEAD commit from the BR2 cache
> KERNEL_HEAD=$(git -C dl/linux/git/ rev-parse $KERNEL_BRANCH)
> ^^^ but I'm not sure how to check to see what the latest revision is
> on the remote branch?

Check 'git ls-remote'.

baruch

-- 
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   - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -
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