[PATCH] bootstd: Replicate the dtb-filename quirks of distroboot

[Heinrich Schuchardt]

On 1/25/23 17:15, Tom Rini wrote:
> On Wed, Jan 25, 2023 at 04:38:53PM +0100, Heinrich Schuchardt wrote:
>> On 1/25/23 04:11, Simon Glass wrote:
>>> For EFI, the distro boot scripts search in three different directories
>>> for the .dtb file. The SOC-based filename fallback is supported only for
>>> 32-bit ARM.
>>>
>>> Adjust the code to mirror this behaviour.
>>>
>>> Signed-off-by: Simon Glass <sjg at chromium.org>
>>> Suggested-by: Mark Kettenis <kettenis at openbsd.org>
>>> ---
>>>
>>>    boot/bootmeth_efi.c | 63 ++++++++++++++++++++++++++++++++++++++-------
>>>    1 file changed, 54 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/boot/bootmeth_efi.c b/boot/bootmeth_efi.c
>>> index 67c972e3fe4..f9544846e68 100644
>>> --- a/boot/bootmeth_efi.c
>>> +++ b/boot/bootmeth_efi.c
>>> @@ -147,25 +147,57 @@ static int distro_efi_check(struct udevice *dev, struct bootflow_iter *iter)
>>>    	return 0;
>>>    }
>>> -static void distro_efi_get_fdt_name(char *fname, int size)
>>> +/**
>>> + * distro_efi_get_fdt_name() - Get the filename for reading the .dtb file
>>> + *
>>> + * @fname: Place to put filename
>>> + * @size: Max size of filename
>>> + * @seq: Sequence number, to cycle through options (0=first)
>>> + * Returns: 0 on success, -ENOENT if the "fdtfile" env var does not exist,
>>> + * -EINVAL if there are no more options
>>> + */
>>> +static int distro_efi_get_fdt_name(char *fname, int size, int seq)
>>>    {
>>>    	const char *fdt_fname;
>>> +	const char *prefix;
>>> +
>>> +	/* select the prefix */
>>> +	switch (seq) {
>>> +	case 0:
>>> +		/* this is the default */
>>> +		prefix = "/dtb";
>>> +		break;
>>> +	case 1:
>>> +		prefix = "";
>>> +		break;
>>> +	case 2:
>>> +		prefix = "/dtb/current";
>>> +		break;
>>> +	default:
>>> +		return log_msg_ret("pref", -EINVAL);
>>> +	}
>>>    	fdt_fname = env_get("fdtfile");
>>>    	if (fdt_fname) {
>>> -		snprintf(fname, size, "dtb/%s", fdt_fname);
>>> +		snprintf(fname, size, "%s/%s", prefix, fdt_fname);
>>>    		log_debug("Using device tree: %s\n", fname);
>>> -	} else {
>>> +
>>> +	/* Use this fallback only for 32-bit ARM */
>>> +	} else if (IS_ENABLED(CONFIG_ARM) && !IS_ENABLED(CONFIG_ARM64)) {
>>>    		const char *soc = env_get("soc");
>>>    		const char *board = env_get("board");
>>>    		const char *boardver = env_get("boardver");
>>>    		/* cf the code in label_boot() which seems very complex */
>>> -		snprintf(fname, size, "dtb/%s%s%s%s.dtb",
>>> +		snprintf(fname, size, "%s/%s%s%s%s.dtb", prefix,
>>>    			 soc ? soc : "", soc ? "-" : "", board ? board : "",
>>>    			 boardver ? boardver : "");
>>>    		log_debug("Using default device tree: %s\n", fname);
>>> +	} else {
>>> +		return log_msg_ret("env", -ENOENT);
>>>    	}
>>> +
>>> +	return 0;
>>>    }
>>>    static int distro_efi_read_bootflow_file(struct udevice *dev,
>>> @@ -174,7 +206,7 @@ static int distro_efi_read_bootflow_file(struct udevice *dev,
>>>    	struct blk_desc *desc = NULL;
>>>    	ulong fdt_addr, size;
>>>    	char fname[256];
>>> -	int ret;
>>> +	int ret, seq;
>>>    	/* We require a partition table */
>>>    	if (!bflow->part)
>>> @@ -196,13 +228,22 @@ static int distro_efi_read_bootflow_file(struct udevice *dev,
>>>    	if (ret)
>>>    		return log_msg_ret("read", -EINVAL);
>>> -	distro_efi_get_fdt_name(fname, sizeof(fname));
>>> +	fdt_addr = env_get_hex("fdt_addr_r", 0);
>>> +
>>> +	/* try the various available names */
>>> +	ret = -ENOENT;
>>> +	for (seq = 0; ret; seq++)
>>
>> There are boards that don't have a dtb file available and that is ok. Don't
>> loop past seq = 2.
>>
>> {
>>> +		ret = distro_efi_get_fdt_name(fname, sizeof(fname), seq);
>>> +		if (ret)
>>> +			return log_msg_ret("nam", ret);
>>> +		ret = bootmeth_common_read_file(dev, bflow, fname, fdt_addr,
>>> +						&size);
>>> +	}
>>> +
>>>    	bflow->fdt_fname = strdup(fname);
>>>    	if (!bflow->fdt_fname)
>>>    		return log_msg_ret("fil", -ENOMEM);
>>
>> This should not be an error. The Distroboot fallback is the device-tree at
>> $fdtcontroladdr.
> 
> But it should note that it's using that because that's still quite often
> an unexpected feature to people.
> 

On QEMU it is just what is needed. Other boards supply the device-tree 
via TF-A or OpenSBI. We should not start breaking boards.

A message "fil: returning err= -12" signals not caring about users.

Best regards

Heinrich