[coreboot] #156: Add Layout File capability to v3 and LAR tool

[coreboot]

#156: Add Layout File capability to v3 and LAR tool
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    Reporter:  edwin_beasant@…              |         Owner:  stepan@…                    
        Type:  enhancement                  |        Status:  new                         
    Priority:  major                        |     Milestone:                              
   Component:  coreboot                     |      Keywords:  flashrom lar layout image v3
Dependencies:                               |   Patchstatus:  patch needs review          
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 This patch adds the ability to specify a layout file within the v3 Kconfig
 menu system, and then to enable LAR to read and setup a flash image with
 respect to this layout file. This operates by padding the blank space with
 '(padding)' images, using a similar method to the zero padding that LAR
 uses to finalise an image.
 I have also included the patch to optionally disable fallback booting:
 this speeds things up a bit on the DB800 board which seems to have RTC
 byte read/write issues somewhere...

 The layout file format is the same as current flashrom.
 It also allows addition/specification of the VSA within the Kconfig setup
 for Geode targets, which will then be added to the LAR in a sensible
 place.
 Example tested layout for 49LF008A device:

 00000000:0003ffff fallback
 00040000:0004ffff vsa
 00050000:0008ffff normal
 000f0000:000f0000 bootblock

 Note that the fallback image is 'below' the normal image:
 This allows for the fallback image to be 'golden': if you repeatedly flash
 the only the 'normal' area, you will always have a working accessible VSA
 and fallback image if the normal flash fails.
 This does not prevent you from flashing the fallback image (just ba
 cautious)...

 This has been tested as working on the Zoom DB800 development platform.

 Comments and review please!

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Ticket URL: <http://tracker.coreboot.org/trac/coreboot/ticket/156>
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