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

[Heinrich Schuchardt <heinrich.schuchardt@canonical.com>]

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"

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)

and find the ESP on it at runtime.

> => 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)/
> 	HD(1,GPT,0ed48d12-1b4c-4e08-b3ee-decf20428036,0x800,0xa000)
>    data:
>      00000000: 00 00
> => efideubg -b 2 USB usb 0:1

efidebug

Best regards

Heinrich

> => efidebug boot order 2 1
> => bootefi bootmgr
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@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);
>   
>