Re: [U-Boot] [PATCH v4 1/3] Add README for the Falcon mode
On 23/11/2012 19:10, Vikram Narayanan wrote: Hi Stefano, Sorry for bumping in at v4. Below are some of my comments. No problems, all reviews are welcome ! I fix your comments in V5. If the offset is known at compile time, why should the end user use the above commands to write it? Can't it be automated? Just an idea. No, it's not - Andreas have already given links to previous threads where this issue was discussed. Best regards, Stefano -- = DENX Software Engineering GmbH, MD: Wolfgang Denk Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sba...@denx.de = ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH v4 1/3] Add README for the Falcon mode
Hello Andreas, On 11/24/2012 3:29 AM, Andreas Bießmann wrote: Dear Vikram Narayanan, On 23.11.12 19:10, Vikram Narayanan wrote: snip +The parameters generated with this step can be saved into NAND at the offset +0x80 (value for twister for CONFIG_CMD_SPL_NAND_OFS) + +nand erase.part bootparms +nand write 0x8100 bootparms 0x4000 If the offset is known at compile time, why should the end user use the above commands to write it? Can't it be automated? Just an idea. No, please read http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/102326 or http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/147205 Thanks. Clarified. Regards, Vikram ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
[U-Boot] [PATCH v4 1/3] Add README for the Falcon mode
Simple howto to add support to a board for booting the kernel from SPL (Falcon mode). Signed-off-by: Stefano Babic sba...@denx.de --- Changes in v4: - fix capitalization, styling, in spl help (Andreas Biessmann) - move CONFIG_SPL_OS_BOOT before function in doc (Andreas Biessmann) Changes in v3: - parameter initrd_addr was removed in V2 (Andreas Biessmann) - added patch to fix help usage for spl export (Andreas Biessmann) - Added empty lines (Otavio Salvador) - add a more exhaustive description explaining that spl export does not save into media (Lukasz Majewski). Changes in v2: - spelling, language fixes (Andreas Biessman) - rewrite some unclear sentences - drop CONFIG_SPL_OS_BOOT_KEY - make example with twister more exhaustive doc/README.falcon | 173 + 1 file changed, 173 insertions(+) create mode 100644 doc/README.falcon diff --git a/doc/README.falcon b/doc/README.falcon new file mode 100644 index 000..1c041ea --- /dev/null +++ b/doc/README.falcon @@ -0,0 +1,173 @@ +U-Boot Falcon Mode + + +Introduction + + +This document provides an overview how to add support for Falcon Mode +to a board. +Falcon Mode is introduced to speed up the booting process, allowing +to boot a Linux kernel (or whatever image) without a full blown U-Boot. + +Falcon Mode relies on the SPL framework. In fact, to make booting faster, +U-Boot is split into two parts: the SPL (Secondary Program Loader) and U-Boot +image. In most implementations, SPL is used to start U-Boot when booting from +a mass storage, such as NAND or SD-Card. SPL has now support for other media, +and can be generalized seen as a way to start an image performing the minimum +required initialization. SPL initializes mainly the RAM controller, and after +that copies U-Boot image into the memory. The Falcon Mode extends this way +allowing to start the Linux kernel directly from SPL. A new command is added +to U-Boot to prepare the parameters that SPL must pass to the kernel, using +ATAGS or Device Tree. + +Falcon Mode adds a command under U-Boot to reuse all code responsible to prepare +the interface with the kernel. In usual U-Boot systems, these parameters are +generated each time before loading the kernel, passing to Linux the address +in memory where the parameters can be read. +With Falcon Mode, this snapshot can be saved into persistent storage and SPL is +informed to load it before running the kernel. + +To boot the kernel, these steps under a Falcon-aware U-Boot are required: + +1. Boot the board into U-Boot. +Use the spl export command to generate the kernel parameters area or the DT. +U-Boot runs as when it boots the kernel, but stops before passing the control +to the kernel. + +2. Save the prepared snapshot into persistent media. +The address where to save it must be configured into board configuration +file (CONFIG_CMD_SPL_NAND_OFS for NAND). + +3. Boot the board into Falcon Mode. SPL will load the kernel and copy +the parameters area to the required address. + +It is required to implement a custom mechanism to select if SPL loads U-Boot +or another image. + +The value of a GPIO is a simple way to operate the selection, as well as +reading a character from the SPL console if CONFIG_SPL_CONSOLE is set. + +Falcon Mode is generally activated by setting CONFIG_SPL_OS_BOOT. This tells +SPL that U-Boot is not the only available image that SPL is able to start. + +Configuration + +CONFIG_CMD_SPL Enable the spl export command. + The command spl export is then available in U-Boot + mode +CONFIG_SYS_SPL_ARGS_ADDR Address in RAM where the parameters must be + copied by SPL. + In most cases, it is start_of_ram + 0x100 + +CONFIG_SYS_NAND_SPL_KERNEL_OFFSOffset in NAND where the kernel is stored + +CONFIG_CMD_SPL_NAND_OFSOffset in NAND where the parameters area was saved. + +CONFIG_CMD_SPL_WRITE_SIZE Size of the parameters area to be copied + +CONFIG_SPL_OS_BOOT Activate Falcon Mode. + A board should implement the following functions: + +Function that a board must implement + + +void spl_board_prepare_for_linux(void) : optional + Called from SPL before starting the kernel + +spl_start_uboot() : required + Returns 0 if SPL starts the kernel, 1 if U-Boot + must be started. + + +Using spl command +- + +spl - SPL configuration + +Usage: + +spl export img=atags|fdt [kernel_addr] [initrd_addr] [fdt_addr ] + +img: atags or fdt +kernel_addr: kernel is loaded as part of the boot process, but it is not started. + This is the address where a kernel image is stored. +initrd_addr: Address of initial ramdisk + can be set to - if fdt_addr without initrd img
Re: [U-Boot] [PATCH v4 1/3] Add README for the Falcon mode
Hi Stefano, Sorry for bumping in at v4. Below are some of my comments. On 11/23/2012 9:01 PM, Stefano Babic wrote: Simple howto to add support to a board for booting the kernel from SPL (Falcon mode). Signed-off-by: Stefano Babicsba...@denx.de --- Changes in v4: - fix capitalization, styling, in spl help (Andreas Biessmann) - move CONFIG_SPL_OS_BOOT before function in doc (Andreas Biessmann) snip diff --git a/doc/README.falcon b/doc/README.falcon new file mode 100644 index 000..1c041ea --- /dev/null +++ b/doc/README.falcon @@ -0,0 +1,173 @@ +U-Boot Falcon Mode + + +Introduction + + +This document provides an overview how to add support for Falcon Mode s/an overview/an overview of/ +to a board. +Falcon Mode is introduced to speed up the booting process, allowing +to boot a Linux kernel (or whatever image) without a full blown U-Boot. + +Falcon Mode relies on the SPL framework. In fact, to make booting faster, +U-Boot is split into two parts: the SPL (Secondary Program Loader) and U-Boot +image. In most implementations, SPL is used to start U-Boot when booting from +a mass storage, such as NAND or SD-Card. SPL has now support for other media, +and can be generalized seen as a way to start an image performing the minimum Rephrase the above line as, and can generally be seen +required initialization. SPL initializes mainly the RAM controller, and after +that copies U-Boot image into the memory. The Falcon Mode extends this way Rephrase .. SPL mainly initializes the RAM controller, and then copies U-boot image to the main memory. +allowing to start the Linux kernel directly from SPL. A new command is added +to U-Boot to prepare the parameters that SPL must pass to the kernel, using +ATAGS or Device Tree. + +Falcon Mode adds a command under U-Boot to reuse all code responsible to prepare Already it is mentioned that 'a new command is added'. The above line is redundant then. Please rephrase it. +the interface with the kernel. In usual U-Boot systems, these parameters are +generated each time before loading the kernel, passing to Linux the address +in memory where the parameters can be read. +With Falcon Mode, this snapshot can be saved into persistent storage and SPL is +informed to load it before running the kernel. + +To boot the kernel, these steps under a Falcon-aware U-Boot are required: + +1. Boot the board into U-Boot. +Use the spl export command to generate the kernel parameters area or the DT. +U-Boot runs as when it boots the kernel, but stops before passing the control +to the kernel. + +2. Save the prepared snapshot into persistent media. +The address where to save it must be configured into board configuration +file (CONFIG_CMD_SPL_NAND_OFS for NAND). + +3. Boot the board into Falcon Mode. SPL will load the kernel and copy +the parameters area to the required address. copy the parameters which is saved in the persistent media to the + +It is required to implement a custom mechanism to select if SPL loads U-Boot +or another image. + +The value of a GPIO is a simple way to operate the selection, as well as +reading a character from the SPL console if CONFIG_SPL_CONSOLE is set. + +Falcon Mode is generally activated by setting CONFIG_SPL_OS_BOOT. This tells +SPL that U-Boot is not the only available image that SPL is able to start. + +Configuration + +CONFIG_CMD_SPL Enable the spl export command. + The command spl export is then available in U-Boot + mode +CONFIG_SYS_SPL_ARGS_ADDR Address in RAM where the parameters must be + copied by SPL. + In most cases, it isstart_of_ram + 0x100 A space in between is and '' + +CONFIG_SYS_NAND_SPL_KERNEL_OFFSOffset in NAND where the kernel is stored + +CONFIG_CMD_SPL_NAND_OFSOffset in NAND where the parameters area was saved. Can the above be renamed to include the word 'PARAMS'? But becomes lengthy. Any suggestions? + +CONFIG_CMD_SPL_WRITE_SIZE Size of the parameters area to be copied + +CONFIG_SPL_OS_BOOT Activate Falcon Mode. + A board should implement the following functions: Is there a big difference between the line above and the one below? +Function that a board must implement + + +void spl_board_prepare_for_linux(void) : optional + Called from SPL before starting the kernel + +spl_start_uboot() : required + Returns 0 if SPL starts the kernel, 1 if U-Boot + must be started. + + +Using spl command +- + +spl - SPL configuration + +Usage: + +spl exportimg=atags|fdt [kernel_addr] [initrd_addr] [fdt_addr ] + +img: atags or fdt +kernel_addr: kernel is loaded as part of the boot process, but it is not started. + This is the address where a kernel image is stored.
Re: [U-Boot] [PATCH v4 1/3] Add README for the Falcon mode
Dear Vikram Narayanan, On 23.11.12 19:10, Vikram Narayanan wrote: snip +The parameters generated with this step can be saved into NAND at the offset +0x80 (value for twister for CONFIG_CMD_SPL_NAND_OFS) + +nand erase.part bootparms +nand write 0x8100 bootparms 0x4000 If the offset is known at compile time, why should the end user use the above commands to write it? Can't it be automated? Just an idea. No, please read http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/102326 or http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/147205 Best regards Andreas Bießmann ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
