Messages in this thread | | | Date | Tue, 18 Jan 2022 22:13:03 +0800 | From | Jisheng Zhang <> | Subject | Re: [PATCH v2 0/5] kexec: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef |
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On Sun, Jan 16, 2022 at 09:38:47PM +0800, Baoquan He wrote: > Hi Jisheng,
Hi Baoquan,
> > On 12/07/21 at 12:05am, Jisheng Zhang wrote: > > Replace the conditional compilation using "#ifdef CONFIG_KEXEC_CORE" > > by a check for "IS_ENABLED(CONFIG_KEXEC_CORE)", to simplify the code > > and increase compile coverage. > > I go through this patchset, You mention the benefits it brings are > 1) simplity the code; > 2) increase compile coverage; > > For benefit 1), it mainly removes the dummy function in x86, arm and > arm64, right?
Another benefit: remove those #ifdef #else #endif usage. Recently, I fixed a bug due to lots of "#ifdefs": http://lists.infradead.org/pipermail/linux-riscv/2021-December/010607.html
> > For benefit 2), increasing compile coverage, could you tell more how it > achieves and why it matters? What if people disables CONFIG_KEXEC_CORE in > purpose? Please forgive my poor compiling knowledge.
Just my humble opinion, let's compare the code::
#ifdef CONFIG_KEXEC_CORE
code block A;
#endif
If KEXEC_CORE is disabled, code block A won't be compiled at all, the preprocessor will remove code block A;
If we convert the code to:
if (IS_ENABLED(CONFIG_KEXEC_CORE)) { code block A; }
Even if KEXEC_CORE is disabled, code block A is still compiled.
Thanks
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