[RFC 3/3] cmd: efidebug: handle booting from removable media

Heinrich Schuchardt heinrich.schuchardt at canonical.com
Wed Nov 10 09:11:48 CET 2021



On 11/10/21 07:24, AKASHI Takahiro wrote:
> On Tue, Nov 09, 2021 at 10:50:37AM +0100, Heinrich Schuchardt wrote:
>> On 11/9/21 02:32, AKASHI Takahiro wrote:
>>> Support for booting from removable media is now added to UEFI boot
>>> manager. Here we should modify efidebug command in order to define
>>> a proper "BootXXXX" variable.
>>>
>>> With this patch applied, you will be able to specify the boot order,
>>> usb and scsi:
>>
>> I guess for a removable device this should work even if the device is not
>> present. But currently:
>>
>> => efidebug boot add -b 1000 USB_present usb 0:1 EFI/BOOT/BOOTARM.EFI
>> => efidebug boot add -b 1000 USB_not_present usb 1:1 EFI/BOOT/BOOTARM.EFI
>> Cannot create device path for "usb 1:1"
> 
> # In the second, I don't expect you to specify the file path,
> # "EFI/BOOT/BOOTARM.EFI", for removable media support.
> 
> Yes, I have been aware of this issue but it is not this-patch specific
> but an existing issue as you clearly mentioned above.
> 
>> A media device path like:
>>
>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/UsbClass(0x0,0x0,0x9,0x0,0x1)/UsbClass(0x781,0x5571,0x0,0x0,0x0)/HD(1,MBR,0x0c449046,0x800,0x800)
>>
>> is not very helpful because the next device that you insert may have a
>> different location of the ESP partition.
>>
>> I think you should store
>>
>> /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/UsbClass(0x0,0x0,0x9,0x0,0x1)/UsbClass(0x781,0x5571,0x0,0x0,0x0)
> 
> Apparently it is promising but actually not because
> "UsbClass(0x781,0x5571,0x0,0x0,0x0)" contains Vendor ID and
> Product ID which can only be retrieved from a real device attached
> to the board.

0x781,0x5571 relates to
Vendor: SanDisk Corp.
Device: Cruzer Fit

This is how Linux sees my OrangePi PC:

$ lsusb
Bus 009 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 007 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 008 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 006 Device 002: ID 0781:5571 SanDisk Corp. Cruzer Fit
Bus 006 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

The bus numbering seems not to be stable:

$ lsusb
Bus 009 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 008 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 007 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 005 Device 002: ID 0781:5571 SanDisk Corp. Cruzer Fit
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 006 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 004 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


And this is in U-Boot:

usb           0  [ + ]   ehci_generic          |   |-- usb at 1c1a000
usb_hub       0  [ + ]   usb_hub               |   |   `-- usb_hub
usb           1  [ + ]   ohci_generic          |   |-- usb at 1c1a400
usb_hub       1  [ + ]   usb_hub               |   |   `-- usb_hub
usb           2  [ + ]   ehci_generic          |   |-- usb at 1c1b000
usb_hub       2  [ + ]   usb_hub               |   |   `-- usb_hub
usb           3  [ + ]   ohci_generic          |   |-- usb at 1c1b400
usb_hub       3  [ + ]   usb_hub               |   |   `-- usb_hub
usb           4  [ + ]   ehci_generic          |   |-- usb at 1c1c000
usb_hub       4  [ + ]   usb_hub               |   |   `-- usb_hub
usb_mass_s    0  [ + ]   usb_mass_storage      |   |       `-- 
usb_mass_storage
blk           1  [   ]   usb_storage_blk       |   |           `-- 
usb_mass_storage.lun0
usb           5  [ + ]   ohci_generic          |   |-- usb at 1c1c400
usb_hub       5  [ + ]   usb_hub               |   |   `-- usb_hub
usb           6  [ + ]   ehci_generic          |   |-- usb at 1c1d000
usb_hub       6  [ + ]   usb_hub               |   |   `-- usb_hub
usb           7  [ + ]   ohci_generic          |   |-- usb at 1c1d400
usb_hub       7  [ + ]   usb_hub               |   |   `-- usb_hub

The location where a USB is plugged is identified by the port of the USB 
hub it is connected to.

I think before we can properly support removable media we will have to 
get the UEFI device path right. We need a node on all of the levels of 
the DM tree of which more than one instance can exist.

Best regards

Heinrich

> 
> I'm not yet sure where "UsbClass(0x0,0x0,0x9,0x0,0x1)" comes from.
> 
> "USB(X, Y)", where X is a parent_port_number and Y is a usb_interface,
> would be a more appropriate candidate for this kind of device path,
> but we don't utilise this form in the current implementation.
> 
>> and find the ESP on it at runtime.
> 
> I don't think the specification requires that the disk is an ESP
> (at least explicitly).
> 
> 
>>> => efidebug -b 1 SCSI scsi 0:1
>>> => efidebug boot dump
>>> Boot0001:
>>> attributes: A-- (0x00000001)
>>>     label: SCSI
>>>     file_path: /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/Scsi(0,0)/
> 
> Contrary to USB, we use Scsi(0,0) for scsi devices but it is NOT identical
> to U-Boot's scsi0 (in boot_targets).
> 
>>> 	HD(1,GPT,0ed48d12-1b4c-4e08-b3ee-decf20428036,0x800,0xa000)
>>>     data:
>>>       00000000: 00 00
>>> => efideubg -b 2 USB usb 0:1
>>
>> efidebug
> 
> OK
> 
> -Takahiro Akashi
> 
>> Best regards
>>
>> Heinrich
>>
>>> => efidebug boot order 2 1
>>> => bootefi bootmgr
>>>
>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
>>> ---
>>>    cmd/efidebug.c | 46 ++++++++++++++++++++++++++++++++++++++++------
>>>    1 file changed, 40 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/cmd/efidebug.c b/cmd/efidebug.c
>>> index a977ca9c72f5..aaf269cdf47d 100644
>>> --- a/cmd/efidebug.c
>>> +++ b/cmd/efidebug.c
>>> @@ -933,6 +933,29 @@ out:
>>>    	return initrd_dp;
>>>    }
>>> +/**
>>> + * count_arguments - count the number of arguments
>>> + * @argc:	Total number of arguments
>>> + * @argv:	Argument array
>>> + * Return:	Number of arguments
>>> + *
>>> + * Count the number of arguments for a given option, "-?"
>>> + * Specifically if the first argument is not "-?", return 0;
>>> + */
>>> +static int count_arguments(int argc, char *const argv[])
>>> +{
>>> +	int i;
>>> +
>>> +	if (argv[0][0] != '-')
>>> +		return 0;
>>> +
>>> +	for (i = 1; i < argc; i++)
>>> +		if (argv[i][0] == '-')
>>> +			break;
>>> +
>>> +	return i;
>>> +}
>>> +
>>>    /**
>>>     * do_efi_boot_add() - set UEFI load option
>>>     *
>>> @@ -945,7 +968,7 @@ out:
>>>     *
>>>     * Implement efidebug "boot add" sub-command. Create or change UEFI load option.
>>>     *
>>> - * efidebug boot add -b <id> <label> <interface> <devnum>[:<part>] <file>
>>> + * efidebug boot add -b <id> <label> <interface> <devnum>[:<part>] [<file>]
>>>     *                   -i <file> <interface2> <devnum2>[:<part>] <initrd>
>>>     *                   -s '<options>'
>>>     */
>>> @@ -979,7 +1002,10 @@ static int do_efi_boot_add(struct cmd_tbl *cmdtp, int flag,
>>>    	argv++; /* 'add' */
>>>    	for (; argc > 0; argc--, argv++) {
>>>    		if (!strcmp(argv[0], "-b")) {
>>> -			if (argc <  5 || lo.label) {
>>> +			int num_args;
>>> +
>>> +			num_args = count_arguments(argc, argv);
>>> +			if (num_args <  5 || num_args > 6 || lo.label) {
>>>    				r = CMD_RET_USAGE;
>>>    				goto out;
>>>    			}
>>> @@ -1000,7 +1026,8 @@ static int do_efi_boot_add(struct cmd_tbl *cmdtp, int flag,
>>>    			utf8_utf16_strncpy(&label, argv[2], label_len);
>>>    			/* file path */
>>> -			ret = efi_dp_from_name(argv[3], argv[4], argv[5],
>>> +			ret = efi_dp_from_name(argv[3], argv[4],
>>> +					       num_args == 5 ? "" : argv[5],
>>>    					       &device_path, &file_path);
>>>    			if (ret != EFI_SUCCESS) {
>>>    				printf("Cannot create device path for \"%s %s\"\n",
>>> @@ -1008,10 +1035,16 @@ static int do_efi_boot_add(struct cmd_tbl *cmdtp, int flag,
>>>    				r = CMD_RET_FAILURE;
>>>    				goto out;
>>>    			}
>>> +			/* if no file name is given, use device_path */
>>> +			if (num_args == 5) {
>>> +				efi_free_pool(file_path);
>>> +				file_path = device_path;
>>> +				device_path = NULL;
>>> +			}
>>>    			fp_size += efi_dp_size(file_path) +
>>>    				sizeof(struct efi_device_path);
>>> -			argc -= 5;
>>> -			argv += 5;
>>> +			argc -= num_args;
>>> +			argv += num_args;
>>>    		} else if (!strcmp(argv[0], "-i")) {
>>>    			if (argc < 3 || initrd_dp) {
>>>    				r = CMD_RET_USAGE;
>>> @@ -1078,7 +1111,8 @@ out:
>>>    	free(data);
>>>    	efi_free_pool(final_fp);
>>>    	efi_free_pool(initrd_dp);
>>> -	efi_free_pool(device_path);
>>> +	if (device_path)
>>> +		efi_free_pool(device_path);
>>>    	efi_free_pool(file_path);
>>>    	free(lo.label);
>>>


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