support i386

[luckyluke]

Basic support for i386, should fix #341

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This change is 

[Rondom]

The symbols added here are not "LKL_ENTRY_POINTS", right? I have no idea what to call the variable used in the objcopy-invocation should be called like insteadm though, So maybe we have one variable that we fill conditionally (if i386) add these thunk-symbols and then unconditionally add LKL_ENTRY_POINTS. As I said, though I have a hard time coming up with a name.

[luckyluke]

ok, i'll update the patch in the next days

[aostrouhhov]

It should be mentioned that, I suppose, different compiler versions are looking for different symbol names: sometimes it is __x86.get_pc_thunk.REG, sometimes __i386.get_pc_thunk.REG or __i686.get_pc_thunk.REG. I don't know how many of them there are.

[luckyluke]

It should be mentioned that, I suppose, different compiler versions are looking for different symbol names

Thank you, I didn't think about that. Any idea how to detect the compiler? From a quick grep I didn't find examples in linux, maybe something like
ifneq ($(shell $(CC) --version | grep gcc),)
to select which compiler-specific symbols to keep? I don't know which compilers can be used except gcc.

[luckyluke]

I tried with 32-bit clang and no modifications are necessary, everything compiles and test pass as well. Unfortunately I can't test other compilers like intel icc.

[thehajime]

I think keep using LKL_ENTRY_POINTS would be nicer.

[luckyluke]

removed the commit with the LKL_ENTRY_POINTS modification

[thehajime]

thanks @luckyluke. the update is fine.

another thought is if we can have CI (circleci) for i386 build/tests. it would be great if you added an i386 build instance for circleci if possible ?

current our CI is running here:

https://circleci.com/gh/lkl/workflows/linux/tree/master

[luckyluke]

Hi @thehajime, thank you for the feedback.
I'll try to add the circleci conf in the next days.

[luckyluke]

Hi @thehajime I added a circleci config on a container I created based on ubuntu i386. This required some more fix for the tests, I guess due to different versions of gcc and btrfs-tools from my debian machine.

[thehajime]

Hi @thehajime I added a circleci config on a container I created based on ubuntu i386.

Thanks ! LGTM.

This required some more fix for the tests, I guess due to different versions of gcc and btrfs-tools from my debian machine.

for the btrfs-tools, it is also useful with newer mkfs.btrfs; my fedora uses btrfs-progs v4.17.1 and this patch fix the issue so, 1589abb is okay.

[thehajime]

@luckyluke for the follow up fix, could you please make a pull request to https://github.com/lkl/lkl-docker/commits/master ? if we could make the image, we may be able to pull the docker image from docker hub (lkldocker/).