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

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

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.

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@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);
> >