On 08/21/2013 08:32 PM, Li, Fei wrote:
>
> In fact, ACPI method also implements reset by writing RESET_VALUE into
> RESET_REG
> port. In our platform, it also uses port 0xCF9. The difference between cold
> and wart reset
> is whether power cycle is involved or not. After all, this is another topic.
>
> From the source code, CF9 boot method are still used by some apple MAC and
> dell
> platforms if I understand correctly.
>
> Back to our patch, if you really concern the effect of cold reboot 0x0E to
> current existed
> platforms, we can set the default value of reboot_mode as REBOOT_WARM.
>
> Does it make sense?
>
Sort-of-kind-of.
The problem here is that "cold" versus "warm" reboot seems to have
slightly different meanings for BIOS (bypass POST) and the CF9 register
(where I presume it is a "deeper" platform reset of some kind ... is it
even well-defined what the semantics are?)
I could be wrong and the cold/warm reset values in CF9 end up having
exactly the same function as the magic BIOS signature does; if so, then
I would like to be told so explicitly, ideally with an explanation about
how it works on the hw level (or a pointer to relevant documentation,
Intel internal docs are fine.)
Finally, again, does this solve a real problem?
-hpa
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