[coreboot] [PATCH] 440BX registered SDRAM support
Keith Hui
buurin at gmail.com
Thu Mar 31 05:38:24 CEST 2011
On Tue, Mar 29, 2011 at 5:34 PM, Stefan Reinauer
<stefan.reinauer at coreboot.org> wrote:
> * Keith Hui <buurin at gmail.com> [110329 06:11]:
>> >> + if ((edosd & 0x84) == 0x84) {
>> >> + edosd = 0x10; // Registered SDRAM
>> >> + } else {
>> >> + // Clear [4:3] in case it's EDO.
>> >> + edosd &= 0x07;
>> >> +// } else if (edosd & 0x02) {
>> > Besides being commented out, this piece of code would never be executed,
>> > as there already is an else case.
>> > Also, modifying edosd in place is semi nice.
>>
>> So is this good, not so good, or bad?
>>
>> I want to know if I should split up edosd.
>
> Please do.
>
And so I did. Signoff in the patch.
edosd was a romcc-inspired trick because variables were a scarce resource.
The nbxecc simplification in this patch completed one full pass of
memtest86+ each with a regular and registered ECC DIMM installed.
With this patch the 440BX romstage is 60 bytes smaller, freeing up an
extra 64 bytes in the image.
Thanks
Keith
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