[U-Boot] [PATCH v2 1/1] efi_loader: bootmgr: support BootNext and BootCurrent variable behavior
Heinrich Schuchardt
xypron.glpk at gmx.de
Tue Mar 5 19:38:40 UTC 2019
On 3/5/19 2:58 AM, AKASHI Takahiro wrote:
> See UEFI v2.7, section 3.1.2 for details of the specification.
>
> With efidebug command, you can run any EFI boot option as follows:
> => efi boot add 1 SHELL ...
> => efi boot add 2 HELLO ...
> => efi boot order 1 2
> => efi bootmgr
> (starting SHELL ...)
>
> => efi boot next 2
> => efi bootmgr
> (starting HELLO ...)
> => env print -e
> <snip ...>
> BootCurrent: {boot,run}(blob)
> 00000000: 02 00 ..
> BootOrder: {boot,run}(blob)
> 00000000: 01 00 02 00 ....
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
Please, use scripts/get_maintainer.pl to determine the correct
recipients. You missed Alex's new email address.
> ---
> lib/efi_loader/efi_bootmgr.c | 40 ++++++++++++++++++++++++++++++++----
> 1 file changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> index 417016102b48..1575c5c09e46 100644
> --- a/lib/efi_loader/efi_bootmgr.c
> +++ b/lib/efi_loader/efi_bootmgr.c
> @@ -141,6 +141,7 @@ static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
> efi_deserialize_load_option(&lo, load_option);
>
> if (lo.attributes & LOAD_OPTION_ACTIVE) {
> + u32 attributes;
> efi_status_t ret;
>
> debug("%s: trying to load \"%ls\" from %pD\n",
> @@ -151,6 +152,16 @@ static void *try_load_entry(uint16_t n, struct efi_device_path **device_path,
> if (ret != EFI_SUCCESS)
> goto error;
>
> + attributes = EFI_VARIABLE_BOOTSERVICE_ACCESS |
> + EFI_VARIABLE_RUNTIME_ACCESS;
> + size = sizeof(n);
> + ret = EFI_CALL(efi_set_variable(
> + L"BootCurrent",
> + (efi_guid_t *)&efi_global_variable_guid,
> + attributes, size, &n));
> + if (ret != EFI_SUCCESS)
> + goto error;
> +
> printf("Booting: %ls\n", lo.label);
> efi_dp_split_file_path(lo.file_path, device_path, file_path);
> }
> @@ -162,21 +173,42 @@ error:
> }
>
> /*
> - * Attempt to load, in the order specified by BootOrder EFI variable, the
> - * available load-options, finding and returning the first one that can
> - * be loaded successfully.
> + * Attempt to load from BootNext or in the order specified by BootOrder
> + * EFI variable, the available load-options, finding and returning
> + * the first one that can be loaded successfully.
> */
> void *efi_bootmgr_load(struct efi_device_path **device_path,
> struct efi_device_path **file_path)
> {
> - uint16_t *bootorder;
> + u16 bootnext, *bootorder;
bootnext has enough space for the terminating \n. That is way too small.
You want to call efi_get_variable() twice. Get the buffer size needed in
the first round. malloc() a buffer. Then actually read the variable.
Finally free() the buffer.
> efi_uintn_t size;
> void *image = NULL;
> int i, num;
> + efi_status_t ret;
>
> bs = systab.boottime;
> rs = systab.runtime;
>
> + /* BootNext */
> + size = sizeof(bootnext);
> + ret = EFI_CALL(efi_get_variable(L"BootNext",
> + (efi_guid_t *)&efi_global_variable_guid,
> + NULL, &size, &bootnext));
> + if (ret == EFI_SUCCESS) {
The expected value of ret for an existing variable of size > 0 is
EFI_BUFFER_TOO_SMALL.
> + /* delete BootNext */
> + ret = EFI_CALL(efi_set_variable(
> + L"BootNext",
> + (efi_guid_t *)&efi_global_variable_guid,
> + 0, 0, &bootnext));
> + if (ret == EFI_SUCCESS) {
Why would loading the boot entry depend on the return value here?
> + image = try_load_entry(bootnext,
Best regards
Heinrich
> + device_path, file_path);
> + if (image)
> + goto error;
> + }
> + }
> +
> + /* BootOrder */
> bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
> if (!bootorder) {
> printf("BootOrder not defined\n");
>
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