Hi Geoff, On Sat, Jan 17, 2015 at 12:23:34AM +0000, Geoff Levand wrote: > This series adds the core support for kexec re-boots on arm64. This v7 of the > series is mainly just a rebase to the latest arm64 for-next/core branch > (v3.19-rc4), and a few very minor changes requested for v6. I haven't looked at the series in detail before, so some of my comments may have already been discussed. > Several things are known to have problems on kexec re-boot: > > spin-table I think that's not too bad, for complete kexec support (SMP->SMP) we can require some CPU unplug mechanism and PSCI is one of them. > FIX: Upgrade system firmware to provide PSCI enable method support or add > missing spin-table support to the kernel. What's the missing spin-table support? > ACPI > ---- > > PROBLEM: The kernel for ACPI based systems does not export a device tree to the > standard user space location of 'proc/device-tree'. Current applications > expect to access device tree information from this standard location. > > WORK-AROUND: Disable ACPI in firmware, OR pass 'acpi=off' on the first stage > kernel command line, OR pass a user specified DTB using the kexec --dtb option. > > FIX: FIX: An interface to expose a binary device tree to user space has been > proposed. User kexec utilities will need to be updated to add support for this > new interface. So the fix here is to boot the second stage kernel with dtb, which means that we mandate the existence of a DT file for any ACPI system. Are there plans to make the kexec'ed kernel reuse the ACPI tables? -- Catalin
