threads / discuss / 29728

git compiled on same distro, different versions

Subject: git compiled on same distro, different versions

## tl;dr

4 messages between Feb 24, 2012 and Feb 27, 2012.

replies: 3people: 4as markdown or json

Neal Kreitzinger· Feb 24, 2012, 21:05 UTC · lore

If I only test a new git version (compiled from git.git source) on RHEL6 before I put it on the RHEL5 box is that sufficient for validation? Should git behave the same on both? If not, why?

We don't have any RHEL5 VM images so it would be much easier for me to test on a RHEL6 VM. I would have to justify the building of a RHEL5 image just for this purpose.

v/r, neal

Junio C Hamano· Feb 24, 2012, 22:08 UTC · re: Neal Kreitzinger · lore

Re: git compiled on same distro, different versions

"Neal Kreitzinger" <neal@rsss.com> writes:

> If I only test a new git version (compiled from git.git source) on RHEL6 
> before I put it on the RHEL5 box is that sufficient for validation?  Should 
> git behave the same on both?  If not, why?

I somehow find this a strange question to ask to Git people; you may have better luck asking the question to RHEL folks.

Having said that, one of the reasons the result may not work, off the top of my head, is that the binary you compiled would expect to link with the system libraries that are available on your RHEL6 installation. If your RHEL5 installation does not have a matching and ABI compatible library to any of them, the resulting binary would obviously not work there.

Neal Kreitzinger· Feb 25, 2012, 00:05 UTC · re: Junio C Hamano · lore

Re: git compiled on same distro, different versions

On 2/24/2012 4:08 PM, Junio C Hamano wrote:

Show 15 quoted lines

> "Neal Kreitzinger"<neal@rsss.com>  writes:
>
>> If I only test a new git version (compiled from git.git source) on RHEL6
>> before I put it on the RHEL5 box is that sufficient for validation?  Should
>> git behave the same on both?  If not, why?
>
> I somehow find this a strange question to ask to Git people; you may have
> better luck asking the question to RHEL folks.
>
> Having said that, one of the reasons the result may not work, off the top
> of my head, is that the binary you compiled would expect to link with the
> system libraries that are available on your RHEL6 installation.  If your
> RHEL5 installation does not have a matching and ABI compatible library to
> any of them, the resulting binary would obviously not work there.
>

"high-level" question: If I compile git 1.7.9.2 (from git.git source) on RHEL6 test-box and test it and conclude that it "works right" is that sufficient for me to then go ahead and compile git 1.7.9.2 on RHEL5 real-box and expect/assume that it will also "work right"? IOW, will they produce the same results? Because if not then I have just potentially broken the real-box.

"low-level" question: I suspect git calls linux commands alot. Git has "plumbing" commands that are not supposed to "break" scripts. Does linux also have "plumbing" commands that are not supposed to "break" scripts? Does git only use linux "plumbing" commands? Because if git commands uses linux "porcelain" then the linux "porcelain" change could cause git to change (not necessarily "break"). Maybe git-porcelain only uses linux-porcelain, and git-plumbing only uses linux-plumbing.

Definitely thanks in advance for any replies!

v/r, neal

Holger Hellmuth· Feb 27, 2012, 15:19 UTC · re: Neal Kreitzinger · lore

Re: git compiled on same distro, different versions

On 25.02.2012 01:05, Neal Kreitzinger wrote:

Show 7 quoted lines

> "high-level" question:
> If I compile git 1.7.9.2 (from git.git source) on RHEL6 test-box and
> test it and conclude that it "works right" is that sufficient for me to
> then go ahead and compile git 1.7.9.2 on RHEL5 real-box and
> expect/assume that it will also "work right"? IOW, will they produce the
> same results? Because if not then I have just potentially broken the
> real-box.

Depends on your thoroughness. I.e. you have to assume that your testing does actually test aspects that are not covered by all the tests included with git (and not detected by hundreds of other users on that platform). In that case you can't guarantee anything, even applying routine security patches to the operating system could potentially break things (and some companies really test every single patch they apply to mission-critical systems).

Show 8 quoted lines

> "low-level" question:
> I suspect git calls linux commands alot. Git has "plumbing" commands
> that are not supposed to "break" scripts. Does linux also have
> "plumbing" commands that are not supposed to "break" scripts? Does git
> only use linux "plumbing" commands? Because if git commands uses linux
> "porcelain" then the linux "porcelain" change could cause git to change
> (not necessarily "break"). Maybe git-porcelain only uses
> linux-porcelain, and git-plumbing only uses linux-plumbing.

As far as I know there is no plumbing/porcelain distinction in the linux kernel. But while the internal interfaces in the kernel change a lot, the external interface (to user space programs like git) is relatively fixed. You can assume that git is adapted to incompatible changes very fast. But nobody can guarantee you that bugs won't make a difference going from one platform to another.