There is a plan to utlize rmodules for loading ramstage as a
relocatable module. However, the rmodule header may change.
In order to provide some wiggle room for changing the contents
of the rmodule header add some padding. This won't stop the need
for coordinating properly between the romstage loader that may be
in readonly flash and rmodule header fields. But it will provide
for a way to make certain assumptions about alignment of the
rmodule's program when the rmodule is compressed in the flash.
Change-Id: I9ac5cf495c0bce494e7eaa3bd2f2bd39889b4c52
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2749
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
A rmodule is short for relocation module. Relocaiton modules are
standalone programs. These programs are linked at address 0 as a shared
object with a special linker script that maintains the relocation
entries for the object. These modules can then be embedded as a raw
binary (objcopy -O binary) to be loaded at any location desired.
Initially, the only arch support is for x86. All comments below apply to
x86 specific properties.
The intial user of this support would be for SMM handlers since those
handlers sometimes need to be located at a dynamic address (e.g. TSEG
region).
The relocation entries are currently Elf32_Rel. They are 8 bytes large,
and the entries are not necessarily in sorted order. An future
optimization would be to have a tool convert the unsorted relocations
into just sorted offsets. This would reduce the size of the blob
produced after being processed. Essentialy, 8 bytes per relocation meta
entry would reduce to 4 bytes.
Change-Id: I2236dcb66e9d2b494ce2d1ae40777c62429057ef
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/2692
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Aaron Durbin