On Mon, Jun 8, 2015 at 11:48 PM, Christoph Hellwig <hch@xxxxxx> wrote: > The description fails to mention the hacks how this is archived. I don't > think the include hackery and otherwise needed exports are acceptable > if with an explanation, though. I've killed the include hackery. > Really - get your fake hardware into qemu right now and don't bother > with trying to hack the subsystem like this. Rest assured that NFIT enabling for QEMU/KVM is well under way, but I disagree that QEMU is the right place to enable unit tests. Here is the updated changelog that appears in "[PATCH v6 20/21] tools/testing/nvdimm: libnvdimm unit test infrastructure": --- tools/testing/nvdimm: libnvdimm unit test infrastructure 'libnvdimm' is the first driver sub-system in the kernel to implement mocking for unit test coverage. The nfit_test module gets built as an external module and arranges for external module replacements of nfit, libnvdimm, nd_pmem, and nd_blk. These replacements use the linker --wrap option to redirect calls to ioremap() + request_mem_region() to custom defined unit test resources. The end result is a fully functional nvdimm_bus, as far as userspace is concerned, but with the capability to perform otherwise destructive tests on emulated resources. Q: Why not use QEMU for this emulation? QEMU is not suitable for unit testing. QEMU's role is to faithfully emulate the platform. A unit test's role is to unfaithfully implement the platform with the goal of triggering bugs in the corners of the sub-system implementation. As bugs are discovered in platforms, or the sub-system itself, the unit tests are extended to backstop a fix with a reproducer unit test. Another problem with QEMU is that it would require coordination of 3 software projects instead of 2 (kernel + libndctl [1]) to maintain and execute the tests. The chances for bit rot and the difficulty of getting the tests running goes up non-linearly the more components involved. Q: Why submit this to the kernel tree instead of external modules in libndctl? Simple, to alleviate the same risk that out-of-tree external modules face. Updates to drivers/nvdimm/ can be immediately evaluated to see if they have any impact on tools/testing/nvdimm/. [1]: https://github.com/pmem/ndctl -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
