From 32105f7fd8faa7bc3d101dcc3eabc0ae1ac375a7 Mon Sep 17 00:00:00 2001 From: Bernhard Walle Date: Thu, 26 Jun 2008 21:54:08 +0200 Subject: [PATCH] x86: find offset for crashkernel reservation automatically This patch removes the need of the crashkernel=...@offset parameter to define a fixed offset for crashkernel reservation. That feature can be used together with a relocatable kernel where the kexec-tools relocate the kernel and get the actual offset from /proc/iomem. The use case is a kernel where the .text+.data+.bss is after 16M physical memory (debug kernel with lockdep on x86_64 can cause that) which caused a major pain in autoconfiguration in our distribution. Also, that patch unifies crashdump architectures a bit since IA64 has that semantics from the very beginning of the kdump port. Signed-off-by: Bernhard Walle Cc: vgoyal@redhat.com Cc: Bernhard Walle Cc: kexec@lists.infradead.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/setup.c | 70 ++++++++++++++++++++++++++++++----------- 1 file changed, 52 insertions(+), 18 deletions(-) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 2ca12d4c88f..b3469898717 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -422,6 +422,34 @@ static void __init reserve_setup_data(void) */ #ifdef CONFIG_KEXEC + +/** + * Reserve @size bytes of crashkernel memory at any suitable offset. + * + * @size: Size of the crashkernel memory to reserve. + * Returns the base address on success, and -1ULL on failure. + */ +unsigned long long find_and_reserve_crashkernel(unsigned long long size) +{ + const unsigned long long alignment = 16<<20; /* 16M */ + unsigned long long start = 0LL; + + while (1) { + int ret; + + start = find_e820_area(start, ULONG_MAX, size, alignment); + if (start == -1ULL) + return start; + + /* try to reserve it */ + ret = reserve_bootmem_generic(start, size, BOOTMEM_EXCLUSIVE); + if (ret >= 0) + return start; + + start += alignment; + } +} + static inline unsigned long long get_total_mem(void) { unsigned long long total; @@ -444,30 +472,36 @@ static void __init reserve_crashkernel(void) ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base); - if (ret == 0 && crash_size > 0) { - if (crash_base <= 0) { - printk(KERN_INFO "crashkernel reservation failed - " - "you have to specify a base address\n"); + if (ret != 0 || crash_size <= 0) + return; + + /* 0 means: find the address automatically */ + if (crash_base <= 0) { + crash_base = find_and_reserve_crashkernel(crash_size); + if (crash_base == -1ULL) { + pr_info("crashkernel reservation failed. " + "No suitable area found.\n"); return; } - - if (reserve_bootmem_generic(crash_base, crash_size, - BOOTMEM_EXCLUSIVE) < 0) { - printk(KERN_INFO "crashkernel reservation failed - " - "memory is in use\n"); + } else { + ret = reserve_bootmem_generic(crash_base, crash_size, + BOOTMEM_EXCLUSIVE); + if (ret < 0) { + pr_info("crashkernel reservation failed - " + "memory is in use\n"); return; } + } - printk(KERN_INFO "Reserving %ldMB of memory at %ldMB " - "for crashkernel (System RAM: %ldMB)\n", - (unsigned long)(crash_size >> 20), - (unsigned long)(crash_base >> 20), - (unsigned long)(total_mem >> 20)); + printk(KERN_INFO "Reserving %ldMB of memory at %ldMB " + "for crashkernel (System RAM: %ldMB)\n", + (unsigned long)(crash_size >> 20), + (unsigned long)(crash_base >> 20), + (unsigned long)(total_mem >> 20)); - crashk_res.start = crash_base; - crashk_res.end = crash_base + crash_size - 1; - insert_resource(&iomem_resource, &crashk_res); - } + crashk_res.start = crash_base; + crashk_res.end = crash_base + crash_size - 1; + insert_resource(&iomem_resource, &crashk_res); } #else static void __init reserve_crashkernel(void) -- 2.41.1