Re: [patch 00/23] x86: Cleanup apic/ioapic/x2apic setup code

[Jiang Liu]

On 2015/1/16 5:22, Thomas Gleixner wrote:
> While reviewing Jiangs interrupt remapping patch set, I had several
> serious WTF moments when trying to understand what that code is doing.
> 
> The main issues I've seen are:
> 
>     - Blindly copy and pasted code
> 
>     - Random places which initialize bits and pieces
> 
>     - Code which got mindlessly expanded with duct tape and glue
>       without considering readability and maintainability.
> 
>     - Missing inline stubs which result in a ifdef nightmare
> 
>     - Superflous inline stubs to artificially avoid sensible ifdefs
> 
> The deeper I looked the more I started to get grumpy about that maze
> and finally sat down and cleaned it up seriously. One bug I fixed on
> the way (surprise, surprise) got folded into Jiangs series which is
> now in tip/x86/apic. The other one is not that crucial and cant be
> fixed in the previous code without adding more mess.
> 
> The following patch series applies on top of tip/x86/apic. It cleans
> up and consolidates the apic/ioapic/x2apic setup functions.
> 
> Please give it a proper review and testing.
Hi Thomas,

Have done following test matrix:
1) Hardware X2apic capable: yes, preenabled by BIOS: no,
   Kernel: x2apic capable smp
1.1) boot: ok
1.2) boot with "nox2apic": ok
1.3) boot with "nointremap": ok with CPU in physical flat mode

2) Hardware X2apic capable: yes, preenabled by BIOS: no,
   Kernel: x2apic incapable smp
2.1) boot: ok

3) Hardware X2apic capable: yes, preenabled by BIOS: yes
3.1) x2apic capable kernel: ok
3.2) x2apic incapable kernel: hang with a blank screen(panic)
   Kernel: x2apic capable smp

4) Hardware X2apic capable: no
4.1) boot x2apic capable smp kernel: ok
4.2) boot x2apic incapable up kernel: ok
4.3) boot xen domain0 with x2apic capable smp kernel: ok

5) x86_32, UP, IO_APIC disabled
5.1) boot: panic with following call stack:
do_ono_initcall()->APIC_init_uniprocessor()->setup_local_APIC().
I can't capture the full log message due to lack of serial console.
It seems we have trouble with:
early_initcall(APIC_init_uniprocessor);

Regards!
Gerry

> 
> Thanks,
> 
> 	tglx
> ---
>  arch/x86/include/asm/smpboot_hooks.h |   68 ------
>  tip/arch/x86/include/asm/apic.h      |   57 +----
>  tip/arch/x86/include/asm/io_apic.h   |    5 
>  tip/arch/x86/kernel/apic/apic.c      |  395 ++++++++++++++++++-----------------
>  tip/arch/x86/kernel/apic/io_apic.c   |   13 -
>  tip/arch/x86/kernel/cpu/common.c     |    2 
>  tip/arch/x86/kernel/smpboot.c        |  113 +++++-----
>  tip/init/main.c                      |   14 -
>  8 files changed, 308 insertions(+), 359 deletions(-)
> 
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