Re: Question regarding CMOS regions.

[<MohammadYounasKhan.P@Dell.com>]

Thanks Ruiyu.

I have some inconsistencies with CMOS regions. Even EDKII uses some CMOS regions.

I have attached the CMOS dump took using RW tool below:
Type:ISA   Port 0070,0071
Width:01
00=56 01=17 02=45 03=17 04=11 05=15 06=04 07=16 
08=08 09=18 0A=26 0B=02 0C=50 0D=80 0E=00 0F=00 
10=00 11=00 12=00 13=00 14=00 15=7B 16=02 17=FF 
18=FF 19=00 1A=00 1B=00 1C=00 1D=00 1E=00 1F=00 
20=00 21=00 22=00 23=00 24=00 25=00 26=00 27=00 
28=00 29=00 2A=00 2B=00 2C=00 2D=00 2E=02 2F=7B 
30=FF 31=FF 32=20 33=00 34=00 35=9D 36=0B 37=00 
38=00 39=00 3A=00 3B=00 3C=00 3D=00 3E=00 3F=00 
40=00 41=00 42=CA 43=B8 44=6C 45=58 46=00 47=00 
48=00 49=00 4A=00 4B=00 4C=00 4D=00 4E=00 4F=00 
50=00 51=00 52=00 53=00 54=03 55=00 56=00 57=00 
58=00 59=00 5A=00 5B=00 5C=00 5D=00 5E=00 5F=00 
60=00 61=00 62=00 63=00 64=00 65=00 66=00 67=00 
68=00 69=00 6A=00 6B=00 6C=01 6D=00 6E=00 6F=A5 
70=00 71=00 72=00 73=00 74=00 75=00 76=00 77=00 
78=00 79=5F 7A=00 7B=00 7C=00 7D=00 7E=00 7F=00 
80=56 81=17 82=45 83=17 84=11 85=15 86=04 87=16 
88=08 89=18 8A=26 8B=02 8C=40 8D=80 8E=00 8F=00 
90=00 91=00 92=00 93=00 94=00 95=7B 96=02 97=FF 
98=FF 99=00 9A=00 9B=00 9C=00 9D=00 9E=00 9F=00 
A0=00 A1=00 A2=00 A3=00 A4=00 A5=00 A6=00 A7=00 
A8=00 A9=00 AA=00 AB=00 AC=00 AD=00 AE=02 AF=7B 
B0=FF B1=FF B2=20 B3=00 B4=00 B5=9D B6=0B B7=00 
B8=00 B9=00 BA=00 BB=00 BC=00 BD=00 BE=00 BF=00 
C0=00 C1=00 C2=CA C3=B8 C4=6C C5=58 C6=00 C7=00 
C8=00 C9=00 CA=00 CB=00 CC=00 CD=00 CE=00 CF=00 
D0=00 D1=00 D2=00 D3=00 D4=03 D5=00 D6=00 D7=00 
D8=00 D9=00 DA=00 DB=00 DC=00 DD=00 DE=00 DF=00 
E0=00 E1=00 E2=00 E3=00 E4=00 E5=00 E6=00 E7=00 
E8=00 E9=00 EA=00 EB=00 EC=01 ED=00 EE=00 EF=A5 
F0=00 F1=00 F2=00 F3=00 F4=00 F5=00 F6=00 F7=00 
F8=00 F9=5F FA=00 FB=00 FC=00 FD=00 FE=00 FF=00

I have update my queries below.

Thank you,
Younas.
-----Original Message-----
From: Ni, Ruiyu [mailto:ruiyu.ni@intel.com] 
Sent: Thursday, August 16, 2018 11:38 AM
To: Pathan, MohammadYounasKhan; edk2-devel@lists.01.org
Subject: RE: Question regarding CMOS regions.

Younas,
Why are you still working on CMOS in now UEFI world?
Detailed answer is in below.

Thanks/Ray

> -----Original Message-----
> From: edk2-devel <edk2-devel-bounces@lists.01.org> On Behalf Of 
> MohammadYounasKhan.P@Dell.com
> Sent: Thursday, August 16, 2018 12:44 PM
> To: edk2-devel@lists.01.org
> Subject: Re: [edk2] Question regarding CMOS regions.
> 
> Hi Guys,
> 
> Please help to reply to my below queries.
> 
> Thank you,
> Younas.
> 
> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of 
> Pathan, MohammadYounasKhan
> Sent: Tuesday, August 14, 2018 9:17 AM
> To: edk2-devel@lists.01.org
> Subject: [edk2] FW: Question regarding CMOS regions.
> 
> Hi All,
> 
> As we know CMOS data can be 128 or 256 bytes. CMOS lower 128 bytes are 
> stored in IO ports 0x70-0x71 whereas CMOS upper 128 bytes are stored 
> using IO ports 0x72-0x73.
> 
>   1.  How to know that the system has 128bytes of CMOS or 256 bytes of 
> CMOS region?
You could read the data to know whether high 128 bytes are valid or not.
[Younas]: How to check the validity of data?

>   2.  Is there any CMOS location which represents CMOS upper region is 
> exists or valid or any other mechanism for it?
Refer to #1.
[Younas]: CMOS upper region means port 0x72-0x73. Each IO port can store 256 bytes of data (0x00-0xFF). Default lower CMOS region has date and time and is valid always. But for upper CMOS region, I am not sure how to check whether it is valid or not?
>   3.  Are we replicating lower 128 bytes to upper 128 bytes in CMOS 
> location
> 0x70-0x71 (or 0x72-0x73)? If yes, Why are we doing that?
It depends on BIOS implementation. I don't see any bios is duplicating the contents.
[Younas]: You can refer to my CMOS dump copied above which shows upper 128bytes have same information as lower 128bytes (of port 0x70-0x71). I would like to know why we are doing this?
> 
> Thank you,
> Younas.
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