On Wed, Aug 27, 2025 at 09:52:21AM +0200, Sebastian Andrzej Siewior wrote: > > this for you, you could also reproduce it before by say doing a large > > direct I/O read. > > On a kernel without that commit in question? Booting Debian's current > v6.12 and > | dd if=vmlinux.o of=/dev/null bs=1G count=1 iflag=direct > > works like a charm. According to strace it does > | openat(AT_FDCWD, "vmlinux.o", O_RDONLY|O_DIRECT) = 3 > | dup2(3, 0) = 0 > | lseek(0, 0, SEEK_CUR) = 0 > | read(0, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\1\0>\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 1073741824) = 841980992 > > so it should be what you asked for. Asked for 1G, got ~800M. This is probably splitting thing up into multiple bios because your output memory is fragmented. You'd have to do it into hugetlbfs or vma otherwise backed by very larger folios.
