On 4/19/22 05:32, Borislav Petkov wrote:
On Mon, Apr 18, 2022 at 05:03:39PM -0500, Eric DeVolder wrote:
I've examined the code with this thought in mind, and I'm not exactly sure how
this code should be restructured for !HOTPLUG stubs. I'd very much appreciate
an example in order to facilitate accommodating the request!
For example, see init_intel_microcode() in arch/x86/include/asm/microcode.h:
#ifdef CONFIG_MICROCODE_INTEL
extern struct microcode_ops * __init init_intel_microcode(void);
#else
static inline struct microcode_ops * __init init_intel_microcode(void)
{
return NULL;
}
#endif /* CONFIG_MICROCODE_INTEL */
The actual definition then is in:
arch/x86/kernel/cpu/microcode/intel.c:
struct microcode_ops * __init init_intel_microcode(void)
and it gets enabled when CONFIG_MICROCODE_INTEL is enabled in the
.config. When CONFIG_MICROCODE_INTEL=n, the static inline stub gets used
and optimized away by the compiler.
HTH.
Thanks Boris. So in taking this concept and looking at, in particular, patch 4/8
"crash: add generic infrastructure for crash hotplug support", I'm not exactly
sure how to apply this technique.
For example, if the suggestion is to change crash_hotplug_init() to be the function
or a stub, then what is an appropriate place to the __init callout?
If instead the suggestion is to create !HOTPLUG stubs() for the registration
functions within crash_hotplug_init(), then that entails taking what are currently
static scope symbols in the callbacks and notifier_block and exposing (ie make non-
static) those, which doesn't seem beneficial.
Or if the suggestion is to create !HOTPLUG stubs() for the callbacks, then I thin that
is implying that crash_hotplug_init() is not #ifdef'd and always runs and always
sets-up these event handlers, regardless if we need them?
Perhaps said differently, I'm not seeing, yet, how this technique applies to this code.
Is there a specific function that you know you want this way?
Thanks,
eric
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