| Message ID | 20201230150722.154663-9-ilias.apalodimas@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Change logic of EFI LoadFile2 protocol for initrd loading | expand |
On 12/30/20 4:07 PM, Ilias Apalodimas wrote: > Add a description of the EFI variables needed to match a Boot#### > entry with an initrd. > > Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> > --- > doc/uefi/uefi.rst | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/doc/uefi/uefi.rst b/doc/uefi/uefi.rst > index dc930d924022..d8b083ffa708 100644 > --- a/doc/uefi/uefi.rst > +++ b/doc/uefi/uefi.rst > @@ -229,6 +229,21 @@ UEFI variables. Booting according to these variables is possible via:: > As of U-Boot v2020.10 UEFI variables cannot be set at runtime. The U-Boot > command 'efidebug' can be used to set the variables. > > +Initrd with the boot manager > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + > +Kernel versions >= 5.6 can use EFI_LOAD_FILE2_PROTOCOL to load an initramfs. %s/can use EFI_LOAD_FILE2_PROTOCOL/can use the Load File 2 protocol/ > +When U-Boot is configured with CONFIG_EFI_LOAD_FILE2_INITRD=y the boot manager > +will install the protocol, if an EFI variable matching the BootCurrent value > +is found and contains a valid file path. The EFI variable name is 'Initrd####' When booting via the UEFI boot manager (command 'bootefi bootmgr') BootNext and BootOrder are used to identify a boot option to boot. The variable BootCurrent is set to the hexadecimal number of the selected boot option, e.g. to 0x001E if the image specified by Boot001E is selected. When U-Boot is configured with CONFIG_EFI_LOAD_FILE2_INITRD=y the boot manager will install the Load File 2 protocol if an EFI variable Initrd#### (e.g. Initrd001E) is found where #### matches the value of BootCurrent and Initrd#### contains a valid file path. > +and the file path format is '<device> <partition> <filename>'. The fist string is not a device but a class of devices. The third string is not a filename but a file path. <interface> <device>[:<partition>] <filepath>. partition defaults to 0 (whole disk). The user should be taught that the value of Initrd#### is a UTF8 string. An example string should be provided. > + > +This allows users to pair a kernel with a specific initramfs. > + > +Example: > +Boot0010 will search for Initrd0010 and try to install the protocol with > +the file path specified in Initrd0010. "When booting Boot001E U-Boot tries to install the Load File 2 protocol with the file specified by Initrd001E. If the intird is not found it will continue without init. What happens if Initrd#### does not point to a valid file? Shouldn't we then skip the boot option and continue with the next boot option? Please, show how to set Initrd0010 from the console, e.g. setenv -e -nv -bs -rt Initrd001E 'scsi 0:1 initrd' Best regards Heinrich > + > Executing the built in hello world application > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > >
diff --git a/doc/uefi/uefi.rst b/doc/uefi/uefi.rst index dc930d924022..d8b083ffa708 100644 --- a/doc/uefi/uefi.rst +++ b/doc/uefi/uefi.rst @@ -229,6 +229,21 @@ UEFI variables. Booting according to these variables is possible via:: As of U-Boot v2020.10 UEFI variables cannot be set at runtime. The U-Boot command 'efidebug' can be used to set the variables. +Initrd with the boot manager +~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Kernel versions >= 5.6 can use EFI_LOAD_FILE2_PROTOCOL to load an initramfs. +When U-Boot is configured with CONFIG_EFI_LOAD_FILE2_INITRD=y the boot manager +will install the protocol, if an EFI variable matching the BootCurrent value +is found and contains a valid file path. The EFI variable name is 'Initrd####' +and the file path format is '<device> <partition> <filename>'. + +This allows users to pair a kernel with a specific initramfs. + +Example: +Boot0010 will search for Initrd0010 and try to install the protocol with +the file path specified in Initrd0010. + Executing the built in hello world application ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Add a description of the EFI variables needed to match a Boot#### entry with an initrd. Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> --- doc/uefi/uefi.rst | 15 +++++++++++++++ 1 file changed, 15 insertions(+) -- 2.30.0