Running MIPS binaries with Qemu - mips

Question

I'm currently attempting to run a MIPS binary using qemu. My host system in Arch linux. As of right now, I've cd'd into the root directory of the firmware where the binary I'm trying to run exists. I've also copied the qemu-mips binary from my host system into the firmware's root directory.
While in the firmware's root directory I was running this command:
sudo chroot . ./qemu-mips bin/busybox
Yet I'm receiving this error:
chroot: failed to run command ‘./qemu-mips’: No such file or directory
This is strange, considering I just copied the qemu-mips binary to the firmware's root directory where I'm currently sitting. Most of the guides I read describing how to do this say to use qemu-mips-static, however even after installing all available qemu tools, that binary does not exist on my system. Is there something glaring that I'm missing? Thank you.
execve("/usr/sbin/chroot", ["chroot", ".", "./qemu-mips", "bin/busybox"], 0x7fffc0804f98 /* 16 vars */) = 0
brk(NULL) = 0x5653dd4e7000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=124268, ...}) = 0
mmap(NULL, 124268, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f209819a000
close(3) = 0
openat(AT_FDCWD, "/usr/lib/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0`\20\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=2069912, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f2098198000
mmap(NULL, 3897584, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f2097bdd000
mprotect(0x7f2097d8b000, 2097152, PROT_NONE) = 0
mmap(0x7f2097f8b000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1ae000) = 0x7f2097f8b000
mmap(0x7f2097f91000, 14576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f2097f91000
close(3) = 0
arch_prctl(ARCH_SET_FS, 0x7f2098199500) = 0
mprotect(0x7f2097f8b000, 16384, PROT_READ) = 0
mprotect(0x5653dcd5b000, 4096, PROT_READ) = 0
mprotect(0x7f20981b9000, 4096, PROT_READ) = 0
munmap(0x7f209819a000, 124268) = 0
brk(NULL) = 0x5653dd4e7000
brk(0x5653dd508000) = 0x5653dd508000
open("/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=1682192, ...}) = 0
mmap(NULL, 1682192, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f2097ffd000
close(3) = 0
getcwd("/home/user/firmware/kkeps-root", 4096) = 46
chroot(".") = 0
chdir("/") = 0
execve("./qemu-mips", ["./qemu-mips", "bin/busybox"], 0x7ffec746eba0 /* 16 vars */) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/charset.alias", O_RDONLY|O_NOFOLLOW) = -1 ENOENT (No such file or directory)
write(2, "chroot: ", 8chroot: ) = 8
write(2, "failed to run command \342\200\230./qemu-"..., 39failed to run command ‘./qemu-mips’) = 39
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, ": No such file or directory", 27: No such file or directory) = 27
write(2, "\n", 1
) = 1
close(1) = 0
close(2) = 0
exit_group(127) = ?
+++ exited with 127 +++
So it appears there are a few things that aren't being found, one of them being /etc/ld.so.preload. I'm not 100% sure what to do about this situation. I'm guessing this has to do with the fact that I am not using the static binary.
EDIT: Fixed by installing qemu-user-static from the AUR.

Answer 1

As you've figured out, this is because you weren't using the statically linked binary. It's not actually strictly necessary to use the static QEMU binary inside a chroot, it's just that for the static binary you need only copy that one file into the chroot, whereas if you use the dynamically linked QEMU you also need to copy in the host dynamic linker and all the host libraries that QEMU links against -- and that can run into problems if the host and the guest want to use the same pathname for dynamic libraries.