[coreboot] Plugin support

Myles Watson mylesgw at gmail.com
Mon Feb 23 19:10:58 CET 2009


On Mon, Feb 23, 2009 at 10:43 AM, Myles Watson <mylesgw at gmail.com> wrote:
> On Mon, Feb 23, 2009 at 10:22 AM, Stefan Reinauer <stepan at coresystems.de> wrote:
>> On 23.02.2009 18:04 Uhr, Myles Watson wrote:
>>> I implemented the *_PLUGIN_SUPPORT config options for v3.  I thought
>>> it was simple since I was just enabling the defines already in the
>>> code.  In retrospect I may have implemented them backward.
>>>
>>> The space in the ROM consumed by PLUGIN_SUPPORT is very small if you
>>> already have support for that bus.  If you don't have support for the
>>> bus it could be significant.  I wanted to make it so that e.g.
>>> HYPERTRANSPORT_PLUGIN_SUPPORT was the default if you had
>>> HYPERTRANSPORT_SUPPORT.  I'd also like people to be able to select
>>> CARDBUS_PLUGIN_SUPPORT or NO_CARDBUS_PLUGIN_SUPPORT.
>>>
>> How much code do all those "plugins" together consume, given you have a
>> system with none of that buses in the dts?
>
> Coreboot ROM Image (QEMU) with no plugin support:
>  normal/option_table (932 bytes @0x50);loadaddress 0x0 entry 0x0
>  normal/initram/segment0 (440 bytes @0x450);loadaddress 0x0 entry 0x0x20
>  normal/stage2/segment0 (194780 bytes, zeroes compressed to 1 bytes
> @0x660);loadaddress 0x0xd130 entry 0x0x2000
>  normal/stage2/segment1 (35188 bytes, lzma compressed to 18410 bytes
> @0x6c0);loadaddress 0x0x2000 entry 0x0x2000
>  normal/stage2/segment2 (6076 bytes, lzma compressed to 360 bytes
> @0x4f00);loadaddress 0x0xb974 entry 0x0x2000
>  bootblock (20480 bytes @0x3b000)
> Total size = 41071B 40KB (0xa06f)
>
> Coreboot ROM Image with all plugins:
>  normal/option_table (932 bytes @0x50);loadaddress 0x0 entry 0x0
>  normal/initram/segment0 (440 bytes @0x450);loadaddress 0x0 entry 0x0x20
>  normal/stage2/segment0 (194784 bytes, zeroes compressed to 1 bytes
> @0x660);loadaddress 0x0xe1c0 entry 0x0x2000
>  normal/stage2/segment1 (39340 bytes, lzma compressed to 20416 bytes
> @0x6c0);loadaddress 0x0x2000 entry 0x0x2000
>  normal/stage2/segment2 (6164 bytes, lzma compressed to 376 bytes
> @0x56d0);loadaddress 0x0xc9ac entry 0x0x2000
>  bootblock (20480 bytes @0x3b000)
> Total size = 43093B 42KB (0xa855)
>
> It looks like about 2K.  In order for it to build I had to define a
> few HT-specific things and put in  an empty mainboard.h, but it won't
> be hard if we want to make it the default to always include all buses.

Coreboot ROM Image with everything but HyperTransport:
  normal/option_table (932 bytes @0x50);loadaddress 0x0 entry 0x0
  normal/initram/segment0 (440 bytes @0x450);loadaddress 0x0 entry 0x0x20
  normal/stage2/segment0 (194784 bytes, zeroes compressed to 1 bytes
@0x660);loadaddress 0x0xda70 entry 0x0x2000
  normal/stage2/segment1 (37468 bytes, lzma compressed to 19388 bytes
@0x6c0);loadaddress 0x0x2000 entry 0x0x2000
  normal/stage2/segment2 (6164 bytes, lzma compressed to 379 bytes
@0x52d0);loadaddress 0x0xc25c entry 0x0x2000
  bootblock (20480 bytes @0x3b000)
Total size = 42068B 41KB (0xa454)

Maybe this is a good middle ground.  I haven't seen a PCI->HT bridge yet :)

Thanks,
Myles

>>> Maybe we could get rid of the *PLUGIN_SUPPORT options all together and
>>> just allow the developer to select CARDBUS_SUPPORT or
>>> REMOVE_CARDBUS_SUPPORT directly?  We don't want people to deselect
>>> HYPERTRANSPORT_SUPPORT when they have an Opteron, though.
>>>
>>
>> If we're talking about a significant amount of code that is disabled, I
>> tend to agree. On the other hand, Ron brought up the very valuable point
>> that we want to try remove as many conditional compilations as possible
>> to keep the code simple (and: testable)
>
> the fewer #ifdefs the better for me too.
>
>>> Could I get some feedback on what people want?  It's very low on my
>>> priority list, but I'm willing to take ownership since I put it there.
>>>
>> Sure.. :-)
>
> Thanks,
> Myles
>




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