On Mon, Sep 28, 2026 at 1:40 PM Bradley Morgan <[email protected]> wrote: > > On 28 September 2026 18:55:34 BST, Zack Rusin <[email protected]> > wrote: > >A VMware guest may have no persistent storage or working userspace after > >a crash. Preserve its newest kernel log tail in the host's vmware.log > >before entering kdump, without enabling every panic notifier by default. > > > >Following Petr's suggestion, add one generic panic_pre_kdump_list with > >VMware as its first client. A set-once helper covers panic() and direct > >crash-kexec entry. Fatal oopses can reach kdump without calling panic(), > >so patch 2 adds that call after capturing the original registers under > >the existing kexec lock. The late panic call follows sys_info() and > >precedes the kmsg dumpers. > > > >Patch 3 adds Guilherme's suggested escape hatch for debugging kdump > >failures involving early callbacks. With panic_pre_kdump_postpone set, > >the list runs before kdump only when crash_kexec_post_notifiers is also > >set. This can omit hypervisor crash handling as well as diagnostics. > >The late panic call remains eligible. This policy is a separate patch; > >I can omit patch 3 if it is not wanted. > > > >The logger preallocates an 8 KiB buffer and bounds its register-based > >RPC transfer and retries. Michael suggested increasing the buffer > >because 4 KiB can omit useful stack-trace context. Ordinary guests > >enable logging by default; encrypted guests must opt in. Use > >bool/proc_dobool for the sysctl as Joel requested. The potentially > >terminating REPORTGUESTCRASH event remains a separate late dumper, > >suppressed whenever a crash image is loaded. The v1 assignment to > >crash_kexec_post_notifiers is dropped. > > > >Tested on VMware Workstation and ESXi with ordinary guests, and on > >ESXi with SEV-SNP and TDX guests. > > > >v1: > >https://lore.kernel.org/r/[email protected] > > > >Zack Rusin (6): > > panic: Add a notifier chain for pre-kdump callbacks > > crash: Notify pre-kdump callbacks before switching kernels > > panic: Allow postponing pre-kdump notifiers > > x86/vmware: Add a bounded pre-kdump log sender > > x86/vmware: Add the vmware_record_panic_msg sysctl > > x86/vmware: Report guest crashes after kmsg dumpers > > > > .../admin-guide/kernel-parameters.txt | 14 + > > Documentation/admin-guide/sysctl/kernel.rst | 20 ++ > > arch/x86/include/asm/vmware.h | 2 + > > arch/x86/kernel/cpu/vmware.c | 250 ++++++++++++++++++ > > include/linux/panic_notifier.h | 4 + > > kernel/crash_core.c | 3 + > > kernel/panic.c | 28 ++ > > 7 files changed, 321 insertions(+) > > > > All the panic changes and crash_core changes looks good to me! > > Reviewed-by: Bradley Morgan <[email protected]> > > Tested basic panic calls with Power10, in courtesy of osuosl: > > Tested-by: Bradley Morgan <[email protected]> # Power10
Thank you for testing! Petr, do you have any thoughts? I think this version addresses all of your concerns/suggestions from v1. z
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