Re: [PATCH v21 1/8] arm64: kdump: reserve memory for crash dump kernel

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Geoff,

Thank you for your reviewing.

On Wed, Jul 06, 2016 at 10:00:18AM -0700, Geoff Levand wrote:
> On Wed, 2016-07-06 at 16:52 +0900, AKASHI Takahiro wrote:
> >  
> > +#ifdef CONFIG_KEXEC_CORE
> > +/*
> > + * reserve_crashkernel() - reserves memory for crash kernel
> > + *
> > + * This function reserves memory area given in "crashkernel=" kernel command
> > + * line parameter. The memory reserved is used by dump capture kernel when
> > + * primary kernel is crashing.
> > + */
> > +static void __init reserve_crashkernel(void)
> > +{
> > +> 	> unsigned long long crash_size = 0, crash_base = 0;
> > +> 	> int ret;
> > +
> > +> 	> ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> > +> 	> 	> 	> 	> &crash_size, &crash_base);
> > +> 	> /* no crashkernel= or invalid value specified */
> > +> 	> if (ret || !crash_size)
> > +> 	> 	> return;
> > +
> > +> 	> if (crash_base == 0) {
> > +> 	> 	> /* Current arm64 boot protocol requires 2MB alignment */
> > +> 	> 	> crash_base = memblock_find_in_range(0,
> > +> 	> 	> 	> 	> MEMBLOCK_ALLOC_ACCESSIBLE, crash_size, SZ_2M);
> > +> 	> 	> if (crash_base == 0) {
> > +> 	> 	> 	> pr_warn("Unable to allocate crashkernel (size:%llx)\n",
> > +> 	> 	> 	> 	> crash_size);
> > +> 	> 	> 	> return;
> > +> 	> 	> }
> > +> 	> 	> memblock_reserve(crash_base, crash_size);
> > +
> > +> 	> } else {
> > +> 	> 	> /* User specifies base address explicitly. */
> > +> 	> 	> if (!memblock_is_region_memory(crash_base, crash_size) ||
> > +> 	> 	> 	> memblock_is_region_reserved(crash_base, crash_size)) {
> > +> 	> 	> 	> pr_warn("crashkernel has wrong address or size\n");
> > +> 	> 	> 	> return;
> > +> 	> 	> }
> > +
> > +> 	> 	> if (!IS_ALIGNED(crash_base, SZ_2M)) {
> > +> 	> 	> 	> pr_warn("crashkernel base address is not 2MB aligned\n");
> > +> 	> 	> 	> return;
> > +> 	> 	> }
> > +
> > +> 	> 	> memblock_reserve(crash_base, crash_size);
> > +> 	> }
> > +
> > +> 	> pr_info("Reserving %lldMB of memory at %lldMB for crashkernel\n",
> > +> 	> 	> crash_size >> 20, crash_base >> 20);
> > +
> > +> 	> crashk_res.start = crash_base;
> > +> 	> crashk_res.end = crash_base + crash_size - 1;
> > +}
> > +#else
> > +static void __init reserve_crashkernel(void)
> > +{
> > +> 	> ;
> > +}
> > +#endif /* CONFIG_KEXEC_CORE */
> > +

I know that this is just a matter of preference, but
I can see more use cases of the above than the below
that you mentioned under arm64 directory.
So I want to keep the current style unchanged unless
the maintainers don't like it.

Thanks,
-Takahiro AKASHI

> I think it is a bit cleaner if you move this conditional
> into the function and have something like:
> 
> static void __init reserve_crashkernel(void)
> {
> #ifdef CONFIG_KEXEC_CORE
> #else
> #endif
> }
>
> -Geoff
> 

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