[coreboot] [RFC] CMOS options
libv at skynet.be
Wed Dec 16 09:39:40 CET 2009
On Sat, Dec 12, 2009 at 02:30:01PM +0100, Stefan Reinauer wrote:
> On 12/11/09 8:39 PM, ron minnich wrote:
> > On Wed, Dec 9, 2009 at 2:57 AM, Andrew Goodbody
> > <andrew.goodbody at tadpole.com> wrote:
> >> Luc Verhaegen wrote:
> >>> We have 892 bytes to our disposal in cmos. We can reserve 128 for
> >>> board/cmos versioning, and reserve even 256 for the bootloader, and still
> >>> have 512bytes left for coreboot options, which is tons when bits are used
> >>> properly and when strings are not used.
> >> Most boards I have used have a maximum space of 256 bytes that includes the
> >> RTC. Where does the extra come from?
> > On much of my hardware, the most I can assume is 128 bytes -
> > subtracting many bytes that are weirdly hardware controlled (such as
> > date).
> > Some of our hardware has 256 bytes.
> > The io ports only support an 8-bit address I thought?
> The ports 0x70/0x71 even only support 7 bits... The 8th bit is used for
> NMI control.
> Higher CMOS bytes can be accessed by 0x72/0x73, 0x74/0x75....
> However, if you try to access the upper 128 bytes by setting the topmost
> bit in 0x70 it will just look like the upper 128 byte are a mirror of
> the lower 128 bytes.
Ah, my bad, i guess 1024 bits is why my synapses brought up that figure.
Still, it should still be possible to segment this up nicely, and then
we suddenly do have a lot of space for bools, sets and integers. And
maybe a string or two to denote the board.
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