Mario Looking at your patches and the preceding discussion on #89050 and having wrapped a cold towel round my head, I have a few comments.
As of kernel 4.17, <https://elixir.bootlin.com/linux/v4.17/source/Documentation/power/swsusp.txt> documents the use of /sys/power/resume_offset to set the offset block, and this is the first version that does actually include the required code in hibernate.c (static ssize_t resume_offset_store(...) line 1070). But that is not the same as the offset parameter sent by /bin/resume. Therefore ... In all cases, the initramfs can only know that it should invoke a resume through the resume kernel parameter. The local-premount/resume script is needed to do this. It has to canonicalise the resume kernel parameter value and pass it via the /sys/power/resume maj:min API. The resume code can use the resume_offset kernel parameter if provided. For kernels before 4.17, the only way to get resume_offset into the resume process is via the kernel command line, either manually or via a function in /etc/default/grub as below invoked during update-grub: Get_Resume() { local sname stype junk roff res swapon --show --noheadings --raw | head -1 | { read sname stype junk if [ "$stype" = "file" ]; then res=`df "$sname" | awk 'END {print $1}'` type swap-offset>/dev/null && # from suspend-utils|uswsusp roff=`swap-offset "$sname" | awk '/resume offset =/ {print $4;exit}'` [ -z "$roff" ] && roff=`filefrag -v "$sname" | awk '{if ($1=="0:") {print substr($4,1,length($4)-2);exit}}'` sname=$res fi # now [ "$stype" = "device" ] res=`lsblk -o PARTUUID --noheadings "$sname"` [ -n "$res" ] && res="resume=PARTUUID=$res" [ -n "$res" ] && [ "$roff" -ge 0 ] && res="$res resume_offset=$roff" echo $res; } } GRUB_CMDLINE_LINUX="`Get_Resume`" I tested a swapfile resume with 4.4 using the echo maj:min:offset>/sys/power/resume API and believed that it worked, but the kernel must have been reading offset from the grub command-line. Whereas for 4.17 and later, you can save the resume device and resume_offset into a conf file for initramfs-tools from a hook run from update-initramfs (which has to happen once for each installed kernel), so long as you replace/update /bin/resume to use the new API. These values override any kernel command-line parameters. The resume_offset parameter remains the default value if the /sys/power/resume_offset API is not used. I can't really see why that's any better than the update-grub approach. There needs to be some global initramfs storage that can be mounted when initiating hibernate/hybrid-sleep and then again by the initramfs when booting. I really have no idea if that's possible. As to the scripts ... hooks/resume <https://salsa.debian.org/superm1-guest/initramfs-tools/commit/f74423c610bd3b9ee9baf97d42bfa0219bfb4826> 1 line 59 For filefrag, e2fsprogs has to be installed. Is it a dependency of other file systems? Should the check on resume_offset be the same as in l63? 2 global If this is going to work with a resume_offset, /sys/power/resume_offset has to be writable. There should be a test "[ -w /sys/power/resume_offset ]" somewhere before writing resume_offset (>0) to the conf file and error if not. scripts/local-premount/resume <https://salsa.debian.org/superm1-guest/initramfs-tools/commit/a39f61e48eca03e264a7235ee984db76e8c10aa9#8609b9b67b65b1556d2a51cfeacee8a080c15af6> Mostly issues with the unpatched source! 1 line 18 Test -e /sys/power/resume should be -w /sys/power/resume. 2 line 29 Test [ -x /bin/plymouth ] but then call plymouth instead of /bin/plymouth - is PATH sure to begin /bin:...? Instead: if type plymouth >/dev/null && plymouth --ping; then 3 line 30 Why not tell the whole truth: plymouth message --text="Resuming from $resume ${resume_offset:+at offset $resume_offset}" 4 line 34 The test is redundant. Replace if ... fi by line 35. There could be a test that resume_offset is an unsigned long number, as in your hooks/resume:63, but then you'd need to handle the error case where resume_offset is set and invalid. 5 lines 35ff /bin/resume <https://github.com/mirror/busybox/blob/master/klibc-utils/resume.c> is no help. It doesn't do what's needed if the resume_offset has been provided from within the initramfs, since it only writes to /sys/power/resume using the never actually implemented maj:min:offset API. You can do the right thing in the script itself per <https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/983805> and avoid possible confusion with uswsusp's resume binary. This is a modified script to handle the 4.17+ API. resume() # resume_device [resume_offset] { local majmin x majmin= # Get the major and minor numbers for the resume device x=$(stat -L -c '0x%t 0x%T' "$1") && majmin=$(printf '%d:%d' $x) [ -n "$majmin" ] && [ "${majmin%:*}" != "0" ] || # No device (could not stat device) or not a real device return 99; [ ! "$2" -ge 0 ] || printf "$2" > /sys/power/resume_offset && printf "$majmin" > /sys/power/resume return $? } Hope that helps. /df -- London SW6 UK
