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

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:

quoted

 
+#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