On 11/27/14 at 02:19pm, Dave Young wrote: > Geoff, > > Is there any Linaro card for the KVM soft restart issue? > > Ccing Andrew Jones since he might be interested in KVM issues. > > On 11/14/14 at 01:22am, Geoff Levand wrote: > > Hi All, > > > > This series adds the core support for kexec re-boots on arm64. I have tested > > with the ARM VE fast model, the ARM Base model and the ARM Foundation > > model with various kernel config options for both the first and second stage > > kernels. > > > > To load a second stage kernel and execute a kexec re-boot on arm64 my patches to > > kexec-tools [2], which have not yet been merged upstream, are needed. > > > > Patches 1-3 rework the arm64 hcall mechanism to give the arm64 soft_restart() > > routine the ability to switch exception levels from EL1 to EL2 for kernels that > > were entered in EL2. > > > > Patch 4 moves proc-macros.S from arm64/mm to arm64/include/asm so that the > > dcache_line_size macro it defines can be uesd by kexec's relocate kernel > > routine. > > > > Patches 5-8 add the actual kexec support. > > > > Please consider all patches for inclusion. Any comments or suggestions on how > > to improve are welcome. > > > > [1] https://git.linaro.org/people/geoff.levand/linux-kexec.git > > [2] https://git.linaro.org/people/geoff.levand/kexec-tools.git > > > > Several things are known to have problems on kexec re-boot: > > > > spin-table > > ---------- > > > > PROBLEM: The spin-table enable method does not implement all the methods needed > > for CPU hot-plug, so the first stage kernel cannot be shutdown properly. > > > > WORK-AROUND: Upgrade to system firmware that provides PSCI enable method > > support, OR build the first stage kernel with CONFIG_SMP=n, OR pass 'maxcpus=1' > > on the first stage kernel command line. > > > > FIX: Upgrade system firmware to provide PSCI enable method support or add > > missing spin-table support to the kernel. > > > > KVM > > --- > > > > PROBLEM: KVM acquires hypervisor resources on startup, but does not free those > > resources on shutdown, so the first stage kernel cannot be shutdown properly. > > > > WORK-AROUND: Build the first stage kernel with CONFIG_KVM=n. > > > > FIX: Fix KVM to support soft_restart(). KVM needs to restore default exception > > vectors, etc. > > > > UEFI > > ---- > > > > PROBLEM: UEFI does not manage its runtime services virtual mappings in a way > > that is compatible with a kexec re-boot, so the second stage kernel hangs on > > boot-up. > > > > WORK-AROUND: Disable UEFI in firmware, OR use EFI uboot emulation if provided > > by your firmware. > > > > FIX: Fix kernel to manage UEFI virtual mappings properly. > > > > /memreserve/ > > ---------- > > > > PROBLEM: The use of device tree /memreserve/ entries is not compatible with > > kexec re-boot. The second stage kernel will use the reserved regions and the > > system will become unstable. > > > > WORK-AROUND: Pass a user specified DTB using the kexec --dtb option. > > > > FIX: Convert device tree source files (.dts) and/or bootloaders to use device > > tree reserved-memory nodes to specify reserved memory or provide an in kernel > > mechanism to export the /memreserve/ entries to user space. > > > > 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 ACPI kernel support to export device tree information suitable for a > > kexec re-boot, and if this information is exported to somewhere other than > > 'proc/device-tree' update existing kexec user applications to use this new > > interface. > > > > ---------------------------------------------------------------- > > The following changes since commit 302cd37c417d59549d073a8986fd028998409cb9: > > > > arm64: kvm: eliminate literal pool entries (2014-11-07 15:04:54 +0000) > > > > are available in the git repository at: > > > > git://git.linaro.org/people/geoff.levand/linux-kexec.git kexec-v6 > > Tested your master branch, works for me with below setup: UEFI boot, CONFIG_KVM=n, maxcpus=1, --lite But --dtb still does not work if there's no /proc/device-tree, failed as below: unrecoverable error: could not scan "/proc/device-tree/": No such file or directory. kexec without --lite also does not work, looks like it hangs after "Bye" .. Thanks Dave
