[pve-devel] [PATCH pve-kernel-meta] proxmox-boot: fix #3632 copy kernel+initrd unconditionally

Stoiko Ivanov s.ivanov at proxmox.com
Thu Sep 23 10:43:17 CEST 2021

do not use the -u (update) flag when copying kernel images and inird
from /boot to the ESPs:
* the ESPs are formatted with vfat, which has a 2 second precision for
  mtime (`linux/fs/fat/misc.c` - `fat_truncate_time`)
* cp -u compares the mtimes of source (kernel image in /boot not on
  vfat) and destination - leading to the copy always being carried
  out, if the source files remain the same (and do not happen to have
  a mtime exactly happening on a even second)

as laid out in the bug-report - the case where this leads to an
unbootable system is when a kernel-version is shipped twice (built
with different tool-chains) - e.g. currently the 5.11 kernels in PVE 6
and PVE 7.

tested the behavior of `cp -u` by running opensnopp-bpfcc and copying
a file twice onto ext4 (opened only once) and on vfat (opened twice).

additionally reproduced the issue (by dist-upgrading a PVE 6 VM to 7
with the pve-no-subscription repo) and verified this patch fixes it.

Signed-off-by: Stoiko Ivanov <s.ivanov at proxmox.com>
Initially considered using the output of `stat --format=%s:%Y` of both
files as 'fingerprint' for comparison

 proxmox-boot/zz-proxmox-boot | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/proxmox-boot/zz-proxmox-boot b/proxmox-boot/zz-proxmox-boot
index 244fe8e..4bd63a6 100755
--- a/proxmox-boot/zz-proxmox-boot
+++ b/proxmox-boot/zz-proxmox-boot
@@ -132,21 +132,21 @@ copy_and_config_kernels() {
 			mkdir -p "${KERNEL_LIVE_DIR}"
-			cp -u --preserve=timestamps "${linux_image}" "${KERNEL_LIVE_DIR}/"
-			cp -u --preserve=timestamps "${initrd}" "${KERNEL_LIVE_DIR}/"
+			cp --preserve=timestamps "${linux_image}" "${KERNEL_LIVE_DIR}/"
+			cp --preserve=timestamps "${initrd}" "${KERNEL_LIVE_DIR}/"
 			# create loader entry
 			cat > "${esp}/loader/entries/proxmox-${kver}.conf" <<- EOF
 				title    ${LOADER_TITLE}
 				version  ${kver}
 				options   ${CMDLINE}
-				linux    /${KERNEL_ESP_DIR}/vmlinuz-${kver}
-				initrd   /${KERNEL_ESP_DIR}/initrd.img-${kver}
+			    linux    /${KERNEL_ESP_DIR}/vmlinuz-${kver}
+			    initrd   /${KERNEL_ESP_DIR}/initrd.img-${kver}
 			warn "	Copying kernel ${kver}"
-			cp -u --preserve=timestamps "${linux_image}" "${esp}/"
-			cp -u --preserve=timestamps "${initrd}" "${esp}/"
+			cp --preserve=timestamps "${linux_image}" "${esp}/"
+			cp --preserve=timestamps "${initrd}" "${esp}/"

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