add bolt_arm64.go for arm64

[jefby]

Support arm64 architecture

Signed-off-by: jefby jef199006@gmail.com

[jefby]

@benbjohnson Hi, could you please check the code? Thanks very much.

[benbjohnson]

👍 thanks!

[drsnyder]

This is causing build errors:

src/github.com/boltdb/bolt/bolt_arm64.go|4 error| maxMapSize redeclared in this block previous declaration at src/github.com/boltdb/bolt/bolt_amd64.go:4                                                                                                                                                                                                                                                                         
src/github.com/boltdb/bolt/bolt_arm64.go|7 error| maxAllocSize redeclared in this block previous declaration at src/github.com/boltdb/bolt/bolt_amd64.go:7

[benbjohnson]

Are you running Go 1.4.x?

[benbjohnson]

I'll move this discussion to #416.

[benbjohnson]

I reverted this change in this PR (#418). I attempted to add build tags to support it in this PR (#417) but no luck.

@jefby If you can get build tags working on Go 1.4 then we can put arm64 support back into Bolt.

[jefby]

@benbjohnson Hi,it can work in go 1.5beta3/1.5/1.5rc1, maybe version 1.4.x is not supported arm64.

[benbjohnson]

It works in 1.5 but the problem is that 1.4 doesn't recognize arm64 as a GOARCH so it doesn't ignore the file. See the other PR for more details.

[dodgerblue]

Any current plans on merging the arm64 support in bolt? From the discussion, I understood that the build fails for Go 1.4.x. However, I am now trying to build Docker 1.9-dev on arm64 and this patch would be the missing piece. What's the current status?

[dodgerblue]

Oh and by the way - Go version is 1.5.

[benbjohnson]

@dodgerblue The issue is that Go 1.4 (and before) don't recognize arm64 as an ARCH so builds fail if bolt_amd64.go is included. It's a tough choice to either support Go 1.4 or Go 1.5. If you can get the arm64 to be ignored by Go 1.4 then I'm cool to merge it in.

[dodgerblue]

@benbjohnson What about #417? Doesn't that fix the issue? I tested that on my machine and got no compile errors (albeit it's not an amd64, but a i386). So if I were to submit a PR, it would be consisted of #414 and #417.

[benbjohnson]

@dodgerblue Hmm, yeah, you're right. If you can submit the PR and test it against Go 1.4 & 1.5 then I'll merge it in. 👍

[hqhq]

@benbjohnson I sent a new PR #435 , added build tag for arm64, I tested it against Go 1.4.2 & 1.5, it works fine.
And I think we can add that kind of build tags for other platform specific files, like other Docker venders such as https://github.com/vishvananda/netns does? I'll sent a new PR soon.

[hqhq]

I checked other vendors, like https://github.com/kr/pty
it only handles build tag for arm64, so maybe we can keep other files as they were.