On 08/13/16 at 12:18am, Thiago Jung Bauermann wrote: > Hello, > > This patch series implements a mechanism which allows the kernel to pass > on a buffer to the kernel that will be kexec'd. This buffer is passed > as a segment which is added to the kimage when it is being prepared > by kexec_file_load. > > How the second kernel is informed of this buffer is architecture-specific. > On powerpc, this is done via the device tree, by checking > the properties /chosen/linux,kexec-handover-buffer-start and > /chosen/linux,kexec-handover-buffer-end, which is analogous to how the > kernel finds the initrd. > > This is needed because the Integrity Measurement Architecture subsystem > needs to preserve its measurement list accross the kexec reboot. The > following patch series for the IMA subsystem uses this feature for that > purpose: > > https://lists.infradead.org/pipermail/kexec/2016-August/016745.html > > This is so that IMA can implement trusted boot support on the OpenPower > platform, because on such systems an intermediary Linux instance running > as part of the firmware is used to boot the target operating system via > kexec. Using this mechanism, IMA on this intermediary instance can > hand over to the target OS the measurements of the components that were > used to boot it. > > Because there could be additional measurement events between the > kexec_file_load call and the actual reboot, IMA needs a way to update the > buffer with those additional events before rebooting. One can minimize > the interval between the kexec_file_load and the reboot syscalls, but as > small as it can be, there is always the possibility that the measurement > list will be out of date at the time of reboot. > > To address this issue, this patch series also introduces > kexec_update_segment, which allows a reboot notifier to change the > contents of the image segment during the reboot process. > > Patch 5 makes kimage_load_normal_segment and kexec_update_segment share > code. It's not much code that they can share though, so I'm not sure if > the result is actually better. > > The last patch is not intended to be merged, it just demonstrates how > this feature can be used. > > This series applies on top of v5 of the "kexec_file_load implementation > for PowerPC" patch series (which applies on top of v4.8-rc1): > > https://lists.infradead.org/pipermail/kexec/2016-August/016843.html I'm trying to review your patches, but seems I can not apply them cleanly to mainline kernel or v4.8-rc1 Apply the kexec_file_load series failed as below on v4.8-rc1: Applying: kexec_file: Allow arch-specific memory walking for kexec_add_buffer error: patch failed: include/linux/kexec.h:149 error: include/linux/kexec.h: patch does not apply Patch failed at 0001 kexec_file: Allow arch-specific memory walking for kexec_add_buffer The copy of the patch that failed is found in: .git/rebase-apply/patch When you have resolved this problem, run "git am --continue". If you prefer to skip this patch, run "git am --skip" instead. To restore the original branch and stop patching, run "git am --abort". What is the order of your patch series of the three patchset? [PATCH v2 0/2] extend kexec_file_load system call [PATCH v5 00/13] kexec_file_load implementation for PowerPC [PATCH v2 0/6] kexec_file: Add buffer hand-over for the next kernel Do they depend on other patches? Thanks Dave
