Hi, thanks for the explanation, I got it now working, with running the kexec call in the background and deleting the initramfs in the foreground after sleep 1. I still think kexec should handle this with less memory needed. greetings tpowa Am Fr., 25. März 2022 um 13:26 Uhr schrieb Philipp Rudo <prudo@xxxxxxxxxx>: > > Hi Tobias, > > On Wed, 23 Mar 2022 12:14:59 +0100 > Tobias Powalowski <tobias.powalowski@xxxxxxxxxxxxxx> wrote: > > > Hi, > > again me, > > I try to load a 900MB ramdisk on a ramfs rootfs with kexec and a 10MB kernel. > > With 2800MB RAM assigned to qemu. > > Memory free by /proc/memstat: 2.2GB > > It keeps on OOM killed while executing: > > kexec -l kernel --initrd=initrd.img > > I can safely unpack the initrd in the ramfs without getting OOM killed. > > What is kexec doing wrong here? > > I don't think that kexec is doing anything wrong here. > > The kexec_load syscall is designed in a way that user space prepares > everything in a huge buffer and passes a pointer to it to the system > call. The systemcall then needs to copy everything from the user buffer > to a kernel buffer. So there are three copies of the initrd in memory > (including the one in ramfs). Together they take up 3 * 900MB = 2.7GB. > So basically all the memory of your guest. > > You can try using the kexec_file_load systemcall. That at least > eliminates the copy in the user buffer so there are only two copies > left. 400MB of free memory is still quite scarce, though. > > Thanks > Philipp > -- Tobias Powalowski Arch Linux Developer & Package Maintainer (tpowa) https://www.archlinux.org tpowa@xxxxxxxxxxxxx St. Martin-Apotheke Herzog-Georg-Str. 25 89415 Lauingen https://www.st-martin-apo.de info@xxxxxxxxxxxxxxxx _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
