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Add support for devicetree files alongside the kernel and initramfs
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Much like the (optional) initramfs at
`/usr/lib/ostree-boot/initramfs-<SHA256>` or
`/usr/lib/modules/$kver/initramfs` you can now optionally include a
flattened devicetree (.dtb) file alongside the kernel at
`/usr/lib/ostree-boot/devicetree-<SHA256>` or
`/usr/lib/modules/$kver/devicetree`.

This is useful for embedded ARM systems which need the devicetree file
loaded by the bootloader for the kernel to discover and initialise
hardware.  See https://en.wikipedia.org/wiki/Device_tree for more
information.

This patch was mostly produced by copy-pasting code for initramfs handling
and renaming `s/initramfs/devicetree/g`.  It's not beautiful, but it is
fairly straightforward.

It may be useful to extend device-tree support in a number ways in the
future.  Device trees dependant on many details of the hardware they
support.  This makes them unlike kernels, which may support many different
hardware variants as long as the instruction-set matches.  This means that
a ostree tree created with a device-tree in this manner will only boot on
a single model of hardware.  This is sufficient for my purposes, but may
not be for others'.

I've tested this on my NVidia Tegra TK1 device which has u-boot running
in syslinux-compatible mode.
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@wmanley
wmanley committed Jan 12, 2018
1 parent 72ebdb8 commit 4cd8917
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Showing 4 changed files with 96 additions and 14 deletions.
2 changes: 1 addition & 1 deletion docs/manual/atomic-upgrades.md
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ collected at any point.
## The /ostree/boot directory

However, we want to optimize for the case where the set of
kernel/initramfs pairs is the same between both the old and new
kernel/initramfs/devicetree sets is the same between both the old and new
deployment lists. This happens when doing an upgrade that does not
include the kernel; think of a simple translation update. OSTree
optimizes for this case because on some systems `/boot` may be on a
Expand Down
9 changes: 5 additions & 4 deletions docs/manual/deployment.md
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Original file line number Diff line number Diff line change
Expand Up @@ -53,10 +53,11 @@ paths, which are `vmlinuz(-.*)?-$checksum` in either `/boot` or `/usr/lib/ostree
The checksum should be a SHA256 hash of the kernel contents; it must be
pre-computed before storing the kernel in the repository. Optionally,
the directory can also contain an initramfs, stored as
`initramfs(-.*)?-$checksum`. If this exists, the checksum must include
both the kernel and initramfs contents. OSTree will use this to
determine which kernels are shared. The rationale for this is to avoid
computing checksums on the client by default.
`initramfs(-.*)?-$checksum` and/or a device tree, stored as
`devicetree(-.*)?-$checksum`. If an initramfs or devicetree exist,
the checksum must include all of the kernel, initramfs and devicetree contents.
OSTree will use this to determine which kernels are shared. The rationale for
this is to avoid computing checksums on the client by default.

The deployment should not have a traditional UNIX `/etc`; instead, it
should include `/usr/etc`. This is the "default configuration". When
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77 changes: 73 additions & 4 deletions src/libostree/ostree-sysroot-deploy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ sysroot_flags_to_copy_flags (GLnxFileCopyFlags defaults,
}

/* Try a hardlink if we can, otherwise fall back to copying. Used
* right now for kernels/initramfs in /boot, where we can just
* right now for kernels/initramfs/device trees in /boot, where we can just
* hardlink if we're on the same partition.
*/
static gboolean
Expand Down Expand Up @@ -894,6 +894,8 @@ typedef struct {
char *kernel_namever;
char *initramfs_srcpath;
char *initramfs_namever;
char *devicetree_srcpath;
char *devicetree_namever;
char *bootcsum;
} OstreeKernelLayout;
static void
Expand All @@ -904,6 +906,8 @@ _ostree_kernel_layout_free (OstreeKernelLayout *layout)
g_free (layout->kernel_namever);
g_free (layout->initramfs_srcpath);
g_free (layout->initramfs_namever);
g_free (layout->devicetree_srcpath);
g_free (layout->devicetree_namever);
g_free (layout->bootcsum);
g_free (layout);
}
Expand Down Expand Up @@ -1025,6 +1029,22 @@ get_kernel_from_tree_usrlib_modules (int deployment_dfd,
if (!ot_gio_splice_update_checksum (NULL, in, &checksum, cancellable, error))
return FALSE;
}
g_clear_object (&in);
glnx_close_fd (&fd);

if (!ot_openat_ignore_enoent (ret_layout->boot_dfd, "devicetree", &fd, error))
return FALSE;
if (fd != -1)
{
ret_layout->devicetree_srcpath = g_strdup ("devicetree");
ret_layout->devicetree_namever = g_strdup_printf ("devicetree-%s", kver);
in = g_unix_input_stream_new (fd, FALSE);
if (!ot_gio_splice_update_checksum (NULL, in, &checksum, cancellable, error))
return FALSE;
}

g_clear_object (&in);
glnx_close_fd (&fd);

char hexdigest[OSTREE_SHA256_STRING_LEN+1];
ot_checksum_get_hexdigest (&checksum, hexdigest, sizeof (hexdigest));
Expand All @@ -1044,6 +1064,7 @@ get_kernel_from_tree_legacy_layouts (int deployment_dfd,
const char *legacy_paths[] = {"usr/lib/ostree-boot", "boot"};
g_autofree char *kernel_checksum = NULL;
g_autofree char *initramfs_checksum = NULL;
g_autofree char *devicetree_checksum = NULL;
g_autoptr(OstreeKernelLayout) ret_layout = _ostree_kernel_layout_new ();

for (guint i = 0; i < G_N_ELEMENTS (legacy_paths); i++)
Expand Down Expand Up @@ -1110,9 +1131,23 @@ get_kernel_from_tree_legacy_layouts (int deployment_dfd,
ret_layout->initramfs_namever = g_strndup (name, dash - name);
}
}
/* See if this is the devicetree */
else if (ret_layout->devicetree_srcpath == NULL && g_str_has_prefix (name, "devicetree-"))
{
const char *dash = strrchr (name, '-');
g_assert (dash);
if (ostree_validate_structureof_checksum_string (dash + 1, NULL))
{
devicetree_checksum = g_strdup (dash + 1);
ret_layout->devicetree_srcpath = g_strdup (name);
ret_layout->devicetree_namever = g_strndup (name, dash - name);
}
}

/* If we found both a kernel and initramfs, break out of the loop */
if (ret_layout->kernel_srcpath != NULL && ret_layout->initramfs_srcpath != NULL)
/* If we found a kernel, an initramfs and a devicetree, break out of the loop */
if (ret_layout->kernel_srcpath != NULL &&
ret_layout->initramfs_srcpath != NULL &&
ret_layout->devicetree_srcpath != NULL)
break;
}

Expand All @@ -1132,6 +1167,19 @@ get_kernel_from_tree_legacy_layouts (int deployment_dfd,
return glnx_throw (error, "Mismatched kernel checksum vs initrd");
}

/* The kernel/devicetree checksums must be the same */
if (ret_layout->devicetree_srcpath != NULL)
{
g_assert (kernel_checksum != NULL);
g_assert (devicetree_checksum != NULL);
if (strcmp (kernel_checksum, devicetree_checksum) != 0)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
"Mismatched kernel checksum vs device tree in tree");
return FALSE;
}
}

ret_layout->bootcsum = g_steal_pointer (&kernel_checksum);

*out_layout = g_steal_pointer (&ret_layout);
Expand Down Expand Up @@ -1567,7 +1615,7 @@ install_deployment_kernel (OstreeSysroot *sysroot,
&deployment_dfd, error))
return FALSE;

/* Find the kernel/initramfs in the tree */
/* Find the kernel/initramfs/devicetree in the tree */
g_autoptr(OstreeKernelLayout) kernel_layout = NULL;
if (!get_kernel_from_tree (deployment_dfd, &kernel_layout,
cancellable, error))
Expand Down Expand Up @@ -1628,6 +1676,21 @@ install_deployment_kernel (OstreeSysroot *sysroot,
}
}

if (kernel_layout->devicetree_srcpath)
{
g_assert (kernel_layout->devicetree_namever);
if (!glnx_fstatat_allow_noent (bootcsum_dfd, kernel_layout->devicetree_namever, &stbuf, 0, error))
return FALSE;
if (errno == ENOENT)
{
if (!hardlink_or_copy_at (kernel_layout->boot_dfd, kernel_layout->devicetree_srcpath,
bootcsum_dfd, kernel_layout->devicetree_namever,
sysroot->debug_flags,
cancellable, error))
return FALSE;
}
}

g_autofree char *contents = NULL;
if (!glnx_fstatat_allow_noent (deployment_dfd, "usr/lib/os-release", &stbuf, 0, error))
return FALSE;
Expand Down Expand Up @@ -1717,6 +1780,12 @@ install_deployment_kernel (OstreeSysroot *sysroot,
_ostree_kernel_args_replace_take (kargs, g_steal_pointer (&prepare_root_arg));
}

if (kernel_layout->devicetree_namever)
{
g_autofree char * boot_relpath = g_strconcat ("/", bootcsumdir, "/", kernel_layout->devicetree_namever, NULL);
ostree_bootconfig_parser_set (bootconfig, "devicetree", boot_relpath);
}

/* Note this is parsed in ostree-impl-system-generator.c */
g_autofree char *ostree_kernel_arg = g_strdup_printf ("ostree=/ostree/boot.%d/%s/%s/%d",
new_bootversion, osname, bootcsum,
Expand Down
22 changes: 17 additions & 5 deletions tests/test-no-initramfs.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

. $(dirname $0)/libtest.sh

echo "1..7"
echo "1..10"

setup_os_repository "archive-z2" "uboot"

Expand All @@ -20,26 +20,29 @@ echo "ok deployment with initramfs"
pull_test_tree() {
kernel_contents=$1
initramfs_contents=$2
devicetree_contents=$3

printf "TEST SETUP:\n kernel: %s\n initramfs: %s\n layout: %s\n" \
"$kernel_contents" "$initramfs_contents" "$layout"
printf "TEST SETUP:\n kernel: %s\n initramfs: %s\n devicetree: %s\n layout: %s\n" \
"$kernel_contents" "$initramfs_contents" "$devicetree_contents" "$layout"

rm -rf ${test_tmpdir}/osdata/usr/lib/modules/3.6.0/{initramfs.img,vmlinuz} \
rm -rf ${test_tmpdir}/osdata/usr/lib/modules/3.6.0/{initramfs.img,vmlinuz,devicetree} \
${test_tmpdir}/osdata/usr/lib/ostree-boot \
${test_tmpdir}/osdata/boot
if [ "$layout" = "/usr/lib/modules" ]; then
# Fedora compatible layout
cd ${test_tmpdir}/osdata/usr/lib/modules/3.6.0
echo -n "$kernel_contents" > vmlinuz
[ -n "$initramfs_contents" ] && echo -n "$initramfs_contents" > initramfs.img
[ -n "$devicetree_contents" ] && echo -n "$devicetree_contents" > devicetree
elif [ "$layout" = "/usr/lib/ostree-boot" ] || [ "$layout" = "/boot" ]; then
# "Legacy" layout
mkdir -p "${test_tmpdir}/osdata/$layout"
cd "${test_tmpdir}/osdata/$layout"
bootcsum=$(echo -n "$kernel_contents$initramfs_contents" \
bootcsum=$(echo -n "$kernel_contents$initramfs_contents$devicetree_contents" \
| sha256sum | cut -f 1 -d ' ')
echo -n "$kernel_contents" > vmlinuz-${bootcsum}
[ -n "$initramfs_contents" ] && echo -n "$initramfs_contents" > initramfs-${bootcsum}
[ -n "$devicetree_contents" ] && echo -n "$devicetree_contents" > devicetree-${bootcsum}
else
exit 1
fi
Expand Down Expand Up @@ -75,4 +78,13 @@ do
assert_not_file_has_content sysroot/boot/loader/entries/ostree-testos-0.conf 'init='

echo "ok switching from no initramfs to initramfs enabled sysroot layout=$layout"

pull_test_tree "the kernel" "" "my .dtb file"
${CMD_PREFIX} ostree admin deploy --os=testos testos:testos/buildmaster/x86_64-runtime

assert_file_has_content sysroot/boot/loader/entries/ostree-testos-0.conf 'init='
assert_file_has_content sysroot/boot/"$(get_key_from_bootloader_conf sysroot/boot/loader/entries/ostree-testos-0.conf 'devicetree')" "my .dtb file"
assert_not_file_has_content sysroot/boot/loader/entries/ostree-testos-0.conf 'initrd'

echo "ok switching from initramfs to no initramfs sysroot with devicetree layout=$layout"
done

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