[16/18] bootstd: Add a simple bootmeth for ChromiumOS

It is possible to boot x86-based ChromeOS machines by parsing a table and
locating the kernel and command line. Add a bootmeth for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

 boot/Kconfig                 |  11 ++
 boot/Makefile                |   1 +
 boot/bootmeth_cros.c         | 212 +++++++++++++++++++++++++++++++++++
 configs/tools-only_defconfig |   1 +
 4 files changed, 225 insertions(+)
 create mode 100644 boot/bootmeth_cros.c

On 4/28/23 21:18, Simon Glass wrote:
> It is possible to boot x86-based ChromeOS machines by parsing a table and
> locating the kernel and command line. Add a bootmeth for this.

What is missing for booting ChromeOS on arm64?

Best regards

Heinrich

>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
>   boot/Kconfig                 |  11 ++
>   boot/Makefile                |   1 +
>   boot/bootmeth_cros.c         | 212 +++++++++++++++++++++++++++++++++++
>   configs/tools-only_defconfig |   1 +
>   4 files changed, 225 insertions(+)
>   create mode 100644 boot/bootmeth_cros.c
>
> diff --git a/boot/Kconfig b/boot/Kconfig
> index d95a2a70266..1dadd42f15e 100644
> --- a/boot/Kconfig
> +++ b/boot/Kconfig
> @@ -462,6 +462,17 @@ config BOOTMETH_GLOBAL
>   	  EFI bootmgr, since they take full control over which bootdevs are
>   	  selected to boot.
>
> +config BOOTMETH_CROS
> +	bool "Bootdev support for Chromium OS"
> +	depends on X86 || SANDBOX
> +	default y
> +	help
> +	  Enables support for booting Chromium OS using bootdevs. This uses the
> +	  kernel A slot and obtains the kernel command line from the parameters
> +	  provided there.
> +
> +	  Note that only x86 devices are supported at present.
> +
>   config BOOTMETH_DISTRO
>   	bool "Bootdev support for distro boot"
>   	select PXE_UTILS
> diff --git a/boot/Makefile b/boot/Makefile
> index 88193a1b60e..998a7f9c684 100644
> --- a/boot/Makefile
> +++ b/boot/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_$(SPL_TPL_)BOOTSTD) += bootstd-uclass.o
>   obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_DISTRO) += bootmeth_distro.o
>   obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_DISTRO_PXE) += bootmeth_pxe.o
>   obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_EFILOADER) += bootmeth_efi.o
> +obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_CROS) += bootmeth_cros.o
>   obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SANDBOX) += bootmeth_sandbox.o
>   obj-$(CONFIG_$(SPL_TPL_)BOOTMETH_SCRIPT) += bootmeth_script.o
>   ifdef CONFIG_$(SPL_TPL_)BOOTSTD_FULL
> diff --git a/boot/bootmeth_cros.c b/boot/bootmeth_cros.c
> new file mode 100644
> index 00000000000..440737060fd
> --- /dev/null
> +++ b/boot/bootmeth_cros.c
> @@ -0,0 +1,212 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Bootmethod for ChromiumOS
> + *
> + * Copyright 2023 Google LLC
> + * Written by Simon Glass <sjg@chromium.org>
> + */
> +
> +#define LOG_CATEGORY UCLASS_BOOTSTD
> +
> +#include <common.h>
> +#include <blk.h>
> +#include <bootdev.h>
> +#include <bootflow.h>
> +#include <bootmeth.h>
> +#include <dm.h>
> +#include <malloc.h>
> +#include <mapmem.h>
> +#include <part.h>
> +#ifdef CONFIG_X86
> +#include <asm/zimage.h>
> +#endif
> +#include <linux/sizes.h>
> +
> +enum {
> +	/* Offsets in the kernel-partition header */
> +	KERN_START	= 0x4f0,
> +	KERN_SIZE	= 0x518,
> +
> +	SETUP_OFFSET	= 0x1000,	/* bytes before base */
> +	CMDLINE_OFFSET	= 0x2000,	/* bytes before base */
> +	OFFSET_BASE	= 0x100000,	/* assumed kernel load-address */
> +};
> +
> +static int cros_check(struct udevice *dev, struct bootflow_iter *iter)
> +{
> +	/* This only works on block and network devices */
> +	if (bootflow_iter_check_blk(iter))
> +		return log_msg_ret("blk", -ENOTSUPP);
> +
> +	return 0;
> +}
> +
> +static int copy_cmdline(const char *from, const char *uuid, char **bufp)
> +{
> +	const int maxlen = 2048;
> +	char buf[maxlen];
> +	char *cmd, *to, *end;
> +	int len;
> +
> +	/* Allow space for cmdline + UUID */
> +	len = strnlen(from, sizeof(buf));
> +	if (len >= maxlen)
> +		return -E2BIG;
> +
> +	log_debug("uuid %d %s\n", uuid ? (int)strlen(uuid) : 0, uuid);
> +	for (to = buf, end = buf + maxlen - UUID_STR_LEN - 1; *from; from++) {
> +		if (to >= end)
> +			return -E2BIG;
> +		if (from[0] == '%' && from[1] == 'U' && uuid &&
> +		    strlen(uuid) == UUID_STR_LEN) {
> +			strcpy(to, uuid);
> +			to += UUID_STR_LEN;
> +			from++;
> +		} else {
> +			*to++ = *from;
> +		}
> +	}
> +	*to = '\0';
> +	len = to - buf;
> +	cmd = strdup(buf);
> +	if (!cmd)
> +		return -ENOMEM;
> +	free(*bufp);
> +	*bufp = cmd;
> +
> +	return 0;
> +}
> +
> +static int cros_read_bootflow(struct udevice *dev, struct bootflow *bflow)
> +{
> +	struct blk_desc *desc = dev_get_uclass_plat(bflow->blk);
> +	ulong base, start, size, setup, cmdline, num_blks, kern_base;
> +	struct disk_partition info;
> +	const char *uuid = NULL;
> +	void *buf, *hdr;
> +	int ret;
> +
> +	log_debug("starting, part=%d\n", bflow->part);
> +
> +	/* We consider the whole disk, not any one partition */
> +	if (bflow->part)
> +		return log_msg_ret("max", -ENOENT);
> +
> +	/* Check partition 2 */
> +	ret = part_get_info(desc, 2, &info);
> +	if (ret)
> +		return log_msg_ret("part", ret);
> +
> +	/* Make a buffer for the header information */
> +	num_blks = SZ_4K >> desc->log2blksz;
> +	log_debug("Reading header, blk=%s, start=%lx, blocks=%lx\n",
> +		  bflow->blk->name, (ulong)info.start, num_blks);
> +	hdr = memalign(SZ_1K, SZ_4K);
> +	if (!hdr)
> +		return log_msg_ret("hdr", -ENOMEM);
> +	ret = blk_read(bflow->blk, info.start, num_blks, hdr);
> +	if (ret != num_blks)
> +		return log_msg_ret("inf", ret);
> +
> +	if (memcmp("CHROMEOS", hdr, 8))
> +		return -ENOENT;
> +
> +	log_debug("Header at %lx\n", (ulong)map_to_sysmem(hdr));
> +	start = *(u32 *)(hdr + KERN_START);
> +	size = ALIGN(*(u32 *)(hdr + KERN_SIZE), desc->blksz);
> +	log_debug("Reading start %lx size %lx\n", start, size);
> +	bflow->size = size;
> +
> +	buf = memalign(SZ_1K, size);
> +	if (!buf)
> +		return log_msg_ret("buf", -ENOMEM);
> +	num_blks = size >> desc->log2blksz;
> +	log_debug("Reading data, blk=%s, start=%lx, blocks=%lx\n",
> +		  bflow->blk->name, (ulong)info.start, num_blks);
> +	ret = blk_read(bflow->blk, (ulong)info.start + 0x80, num_blks, buf);
> +	if (ret != num_blks)
> +		return log_msg_ret("inf", ret);
> +	base = map_to_sysmem(buf);
> +
> +	setup = base + start - OFFSET_BASE - SETUP_OFFSET;
> +	cmdline = base + start - OFFSET_BASE - CMDLINE_OFFSET;
> +	kern_base = base + start - OFFSET_BASE + SZ_16K;
> +	log_debug("base %lx setup %lx, cmdline %lx, kern_base %lx\n", base,
> +		  setup, cmdline, kern_base);
> +
> +#ifdef CONFIG_X86
> +	const char *version;
> +
> +	version = zimage_get_kernel_version(map_sysmem(setup, 0),
> +					    map_sysmem(kern_base, 0));
> +	log_debug("version %s\n", version);
> +	if (version)
> +		bflow->name = strdup(version);
> +#endif
> +	if (!bflow->name)
> +		bflow->name = strdup("ChromeOS");
> +	if (!bflow->name)
> +		return log_msg_ret("nam", -ENOMEM);
> +	bflow->os_name = strdup("ChromeOS");
> +	if (!bflow->os_name)
> +		return log_msg_ret("os", -ENOMEM);
> +
> +#if CONFIG_IS_ENABLED(PARTITION_UUIDS)
> +	uuid = info.uuid;
> +#endif
> +	ret = copy_cmdline(map_sysmem(cmdline, 0), uuid, &bflow->cmdline);
> +	if (ret)
> +		return log_msg_ret("cmd", ret);
> +
> +	bflow->state = BOOTFLOWST_READY;
> +	bflow->buf = buf;
> +	bflow->x86_setup = map_sysmem(setup, 0);
> +
> +	return 0;
> +}
> +
> +static int cros_read_file(struct udevice *dev, struct bootflow *bflow,
> +			 const char *file_path, ulong addr, ulong *sizep)
> +{
> +	return -ENOSYS;
> +}
> +
> +static int cros_boot(struct udevice *dev, struct bootflow *bflow)
> +{
> +#ifdef CONFIG_X86
> +	zboot_start(map_to_sysmem(bflow->buf), bflow->size, 0, 0,
> +		    map_to_sysmem(bflow->x86_setup),
> +		    bflow->cmdline);
> +#endif
> +
> +	return log_msg_ret("go", -EFAULT);
> +}
> +
> +static int cros_bootmeth_bind(struct udevice *dev)
> +{
> +	struct bootmeth_uc_plat *plat = dev_get_uclass_plat(dev);
> +
> +	plat->desc = "ChromiumOS boot";
> +
> +	return 0;
> +}
> +
> +static struct bootmeth_ops cros_bootmeth_ops = {
> +	.check		= cros_check,
> +	.read_bootflow	= cros_read_bootflow,
> +	.read_file	= cros_read_file,
> +	.boot		= cros_boot,
> +};
> +
> +static const struct udevice_id cros_bootmeth_ids[] = {
> +	{ .compatible = "u-boot,cros" },
> +	{ }
> +};
> +
> +U_BOOT_DRIVER(bootmeth_cros) = {
> +	.name		= "bootmeth_cros",
> +	.id		= UCLASS_BOOTMETH,
> +	.of_match	= cros_bootmeth_ids,
> +	.ops		= &cros_bootmeth_ops,
> +	.bind		= cros_bootmeth_bind,
> +};
> diff --git a/configs/tools-only_defconfig b/configs/tools-only_defconfig
> index 23e1f0e9dba..7b6c07ffb02 100644
> --- a/configs/tools-only_defconfig
> +++ b/configs/tools-only_defconfig
> @@ -9,6 +9,7 @@ CONFIG_FIT=y
>   CONFIG_TIMESTAMP=y
>   CONFIG_FIT_SIGNATURE=y
>   # CONFIG_BOOTSTD_FULL is not set
> +# CONFIG_BOOTMETH_CROS is not set
>   # CONFIG_BOOTMETH_VBE is not set
>   CONFIG_USE_BOOTCOMMAND=y
>   CONFIG_BOOTCOMMAND="run distro_bootcmd"

Hi Heinrich,

On Fri, 28 Apr 2023 at 13:51, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
>
> On 4/28/23 21:18, Simon Glass wrote:
> > It is possible to boot x86-based ChromeOS machines by parsing a table and
> > locating the kernel and command line. Add a bootmeth for this.
>
> What is missing for booting ChromeOS on arm64?

Well it uses FIT, but apart from that, not much, probably. I wanted to
get this in before the merge window, so tried not to bite off too
much.

I will see what it takes to get this running on Bob and send a follow-up.

Regards,
Simon

On Sat, Apr 29, 2023 at 3:21 AM Simon Glass <sjg@chromium.org> wrote:
>
> It is possible to boot x86-based ChromeOS machines by parsing a table and
> locating the kernel and command line. Add a bootmeth for this.
>
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
>
>  boot/Kconfig                 |  11 ++
>  boot/Makefile                |   1 +
>  boot/bootmeth_cros.c         | 212 +++++++++++++++++++++++++++++++++++
>  configs/tools-only_defconfig |   1 +
>  4 files changed, 225 insertions(+)
>  create mode 100644 boot/bootmeth_cros.c
>

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>