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authorBernhard Walle <bwalle@suse.de>2008-05-14 18:40:40 -0400
committerTony Luck <tony.luck@intel.com>2008-05-14 18:40:40 -0400
commit8a3360f06cd4d3b1d57f73e029f2f8b6057fdcba (patch)
tree299eee7ef2848e29cec8894fd9e13c7151771c21 /arch/ia64/kernel/setup.c
parent2224661494278bfc1c35b392cf6ee6f58e1d5e64 (diff)
[IA64] Don't reserve crashkernel memory > 4 GB
Some IA64 machines map all cell-local memory above 4 GB (32 bit limit). However, in most cases, the kernel needs some memory below that limit that is DMA-capable. So in this machine configuration, the crashkernel will be reserved above 4 GB. For machines that use SWIOTLB implementation because they lack an I/O MMU the low memory is required by the SWIOTLB implementation. In that case, it doesn't make sense to reserve the crashkernel at all because it's unusable for kdump. A special case is the "hpzx1" machine vector. In theory, it has a I/O MMU, so it can be booted above 4 GB. However, in the kdump case that is not possible because of changeset 51b58e3e26ebfb8cd56825c4b396ed251f51dec9: On HP zx1 machines, the 'machvec=dig' parameter is needed for the kdump kernel to avoid problems with the HP sba iommu. The problem is that during the boot of the kdump kernel, the iommu is re-initialized, so in-flight DMA from improperly shutdown drivers causes an IOTLB miss which leads to an MCA. With kdump, the idea is to get into the kdump kernel with as little code as we can, so shutting down drivers properly is not an option. The workaround is to add 'machvec=dig' to the kdump kernel boot parameters. This makes the kdump kernel avoid using the sba iommu altogether, leaving the IOTLB intact. Any ongoing DMA falls harmlessly outside the kdump kernel. After the kdump kernel reboots, all devices will have been shutdown properly and DMA stopped. This patch pushes that functionality into the sba iommu initialization code, so that users won't have to find the obscure documentation telling them about 'machvec=dig'. This means that also for hpzx1 it's not possible to boot when all memory is above the 4 GB limit. So the only machine vectors that can handle this case are "sn2" and "uv". Signed-off-by: Bernhard Walle <bwalle@suse.de> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel/setup.c')
-rw-r--r--arch/ia64/kernel/setup.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 5015ca1275ca..e9596cd0cdab 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -239,6 +239,25 @@ __initcall(register_memory);
239 239
240 240
241#ifdef CONFIG_KEXEC 241#ifdef CONFIG_KEXEC
242
243/*
244 * This function checks if the reserved crashkernel is allowed on the specific
245 * IA64 machine flavour. Machines without an IO TLB use swiotlb and require
246 * some memory below 4 GB (i.e. in 32 bit area), see the implementation of
247 * lib/swiotlb.c. The hpzx1 architecture has an IO TLB but cannot use that
248 * in kdump case. See the comment in sba_init() in sba_iommu.c.
249 *
250 * So, the only machvec that really supports loading the kdump kernel
251 * over 4 GB is "sn2".
252 */
253static int __init check_crashkernel_memory(unsigned long pbase, size_t size)
254{
255 if (ia64_platform_is("sn2") || ia64_platform_is("uv"))
256 return 1;
257 else
258 return pbase < (1UL << 32);
259}
260
242static void __init setup_crashkernel(unsigned long total, int *n) 261static void __init setup_crashkernel(unsigned long total, int *n)
243{ 262{
244 unsigned long long base = 0, size = 0; 263 unsigned long long base = 0, size = 0;
@@ -252,6 +271,16 @@ static void __init setup_crashkernel(unsigned long total, int *n)
252 base = kdump_find_rsvd_region(size, 271 base = kdump_find_rsvd_region(size,
253 rsvd_region, *n); 272 rsvd_region, *n);
254 } 273 }
274
275 if (!check_crashkernel_memory(base, size)) {
276 pr_warning("crashkernel: There would be kdump memory "
277 "at %ld GB but this is unusable because it "
278 "must\nbe below 4 GB. Change the memory "
279 "configuration of the machine.\n",
280 (unsigned long)(base >> 30));
281 return;
282 }
283
255 if (base != ~0UL) { 284 if (base != ~0UL) {
256 printk(KERN_INFO "Reserving %ldMB of memory at %ldMB " 285 printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
257 "for crashkernel (System RAM: %ldMB)\n", 286 "for crashkernel (System RAM: %ldMB)\n",