From mboxrd@z Thu Jan 1 00:00:00 1970 From: takahiro.akashi@linaro.org (AKASHI Takahiro) Date: Tue, 9 Jan 2018 14:02:18 +0900 Subject: arm64 crashkernel fails to boot on acpi-only machines due to ACPI regions being no longer mapped as NOMAP In-Reply-To: <20171226065636.GA5354@dhcp-128-65.nay.redhat.com> References: <20171221103440.GJ28046@linaro.org> <20171222083308.cy3vwlyhig22q5ee@fireball> <20171225032500.GA8877@linaro.org> <20171226013217.GA2119@dhcp-128-65.nay.redhat.com> <20171226013517.GA2186@dhcp-128-65.nay.redhat.com> <20171226022807.GB8877@linaro.org> <20171226065636.GA5354@dhcp-128-65.nay.redhat.com> Message-ID: <20180109050216.GB18820@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Dec 26, 2017 at 02:56:36PM +0800, Dave Young wrote: > On 12/26/17 at 11:28am, AKASHI Takahiro wrote: > > On Tue, Dec 26, 2017 at 09:35:17AM +0800, Dave Young wrote: > > > [snip] > > > > > > Well, we may be able to change pr_warn() to pr_warn_once() here, but > > > > > > I hope that adding "numa=off" to kernel command line should also work. > > > > > > > > > > Hmm, adding "numa=off" to crashkernel bootargs works, and TBH it was > > > > > my initial thought process as well, but I am not sure if this will > > > > > cause any regressions on aarch64 systems which use crashdump feature. > > > > > > > > It should be fine since we use numa=off by default for all other arches > > > > ie. x86, ppc64 and s390. Actually disabling numa in kdump kernel can save > > > > mm component memory usage. > > > > > > > > > > Forgot to say I means in RHEL and Fedora we use numa=off for kdump.. > > > > Thank you for the clarification. > > (It might be better to make numa off automatically if maxcpus == 0 (and 1?).) > > Hmm, I did a quick test with qemu/kvm, kdump kernel boot without numa=off > I'm not sure why I do not see the warning messages on x86 > machines, maybe something arm64 specific? I didn't see the messages(i.e. "potential offnode page_structs") on arm64 qemu (with -smp 2 -numa node -numa node). It seems that qemu doesn't generate acpi slit(inter-node distance table). Thanks, -Takahiro AKASHI > > > > -Takahiro AKASHI