Heinrich,
On Fri, Mar 08, 2019 at 08:06:06AM +0100, Heinrich Schuchardt wrote:
> On 3/8/19 2:29 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.aka...@linaro.org>
> > ---
> > lib/efi_loader/efi_bootmgr.c | 54 +++++++++++++++++++++++++++++++++---
> > 1 file changed, 50 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> > index 417016102b48..64fc4449446b 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 +173,56 @@ 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;
> > efi_uintn_t size;
> > void *image = NULL;
> > int i, num;
> > + efi_status_t ret;
> >
> > bs = systab.boottime;
> > rs = systab.runtime;
> >
> > + /* BootNext */
> > + bootnext = 0;
> > + 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) {
>
> if (ret == EFI_SUCCESS && size == sizeof(u16))
As I said before, even if size == 1 (byte), the system can
work perfectly, but I don't care any more.
> If we do not check the size the user will never be informed that his
> system is corrupted.
>
> > + /* delete BootNext */
> > + ret = EFI_CALL(efi_set_variable(
> > + L"BootNext",
> > + (efi_guid_t *)&efi_global_variable_guid,
> > + 0, 0, &bootnext));
> > + if (ret == EFI_SUCCESS) {
> > + image = try_load_entry(bootnext,
> > + device_path, file_path);
> > + if (image)
> > + return image;
> > + } else {
> > + printf("BootNext note deleted\n");
>
> %s/note/not/
>
> "Deleting BootNext failed\n" would make it clearer that this is an error.
>
>
> > + }
> > + } else if (ret != EFI_NOT_FOUND) {
> > + if (ret == EFI_BUFFER_TOO_SMALL)
> > + printf("BootNext must be 16-bit integer\n");
> > +
> > + /* delete BootNext */
> > + ret = EFI_CALL(efi_set_variable(
> > + L"BootNext",
> > + (efi_guid_t *)&efi_global_variable_guid,
> > + 0, 0, &bootnext));
> > + if (ret != EFI_SUCCESS)
> > + printf("BootNext note deleted\n");
>
> %s/note/not/
>
> Or maybe "Deleting BootNext failed\n"
>
> The same logic can be implemented without duplicate code but with size
> check:
>
> /* 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_NOT_FOUND) {
> if (ret == EFI_BUFFER_TOO_SMALL || size != sizeof(u16))
> printf("BootNext must be 16-bit integer\n");
> /* delete BootNext */
> ret = EFI_CALL(efi_set_variable(L"BootNext",
> (efi_guid_t
> *)&efi_global_variable_guid,
> 0, 0, &bootnext));
> if (ret != EFI_SUCCESS)
> printf("Deleting BootNext failed\n");
> }
> if (ret == EFI_SUCCESS && size == sizeof(u16)) {
> image = try_load_entry(bootnext,
> device_path, file_path);
> if (image)
> return image;
> }
Strictly speaking, this code doesn't work correctly.
If
* get_variable() failed for some reason (neither NOT_FOUND nor
BUFFER_TOO_SMALL), then "size" still remains to be 2, and
* set_variable() succeeded, then "ret" got EFI_SUCCESS,
"if (ret == EFI_SUCCESS && size == sizeof(u16))" will wrongly match.
I will fix this issue any way in v4, but the code will look a bit ugly.
Thanks,
-Takahiro Akashi
> Best regards
>
> Heinrich
>
> > + }
> > +
> > + /* BootOrder */
> > bootorder = get_var(L"BootOrder", &efi_global_variable_guid, &size);
> > if (!bootorder) {
> > printf("BootOrder not defined\n");
> >
>
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