From b0f9dcabe96e5689ecfba9b6abcd27e685eabd48 Mon Sep 17 00:00:00 2001 From: Michael Chang Date: Wed, 11 May 2022 09:56:11 -0400 Subject: [PATCH] ofdisk: improve boot time by lookup boot disk first While booting lvm, grub will try to build up logical volumes via hooks to disk iteration where on-disk metadata can be read and parsed. However the process can become very slow on multipath as reachable disks are duplicated by multiple I/O paths and they all get inspected. Fortunately grub allows lvm to be lazy binding and opportunistic that root volume can be created when it's needed using a smaller set of discovered disks. The disk iteration can also be controlled by pull methods to only returning specified disks. That said we may be able to take advantage of existing design to cause less overhead in lvm construction. This patch will return boot disks in OpenFirmware so they can be used first. If lvm managed to create root volume out of those boot disks then it is all very nice as they are readily available. Otherwise disk scanning will be performed to present all discoverable disks to grub as what it was done in the past. The result maybe again time consuming but we have nothing to lose here. Signed-off-by: Michael Chang --- grub-core/disk/ieee1275/ofdisk.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/grub-core/disk/ieee1275/ofdisk.c +++ b/grub-core/disk/ieee1275/ofdisk.c @@ -491,10 +491,11 @@ { unsigned i; - if (pull != GRUB_DISK_PULL_NONE) + if (pull > GRUB_DISK_PULL_REMOVABLE) return 0; - scan (); + if (pull == GRUB_DISK_PULL_REMOVABLE) + scan (); for (i = 0; i < ARRAY_SIZE (ofdisk_hash); i++) { @@ -532,6 +533,12 @@ if (!ent->is_boot && ent->is_removable) continue; + if (pull == GRUB_DISK_PULL_NONE && !ent->is_boot) + continue; + + if (pull == GRUB_DISK_PULL_REMOVABLE && ent->is_boot) + continue; + if (hook (ent->grub_shortest, hook_data)) return 1; }