[coreboot] Mistery of the function: static void enable_rom_caching(void)

[Qureshi, Rizwan]

Hi Zoran,
                For skylake refer src/soc/intel/skylake/bootblock/cache_as_ram.S around line 256. We are marking the ROMregion as WP and cacheable and programming an MTRR appropriately.
So, it’s not removed buts its being done while setting up Cache As Ram.

Regards,
Rizwan Qureshi


From: Zoran Stojsavljevic [mailto:zoran.stojsavljevic at gmail.com]
Sent: Monday, August 8, 2016 12:33 PM
To: coreboot <coreboot at coreboot.org>; Paul Menzel <paulepanter at users.sourceforge.net>
Cc: Qureshi, Rizwan <rizwan.qureshi at intel.com>; Ch, Naveenkrishna <naveenkrishna.ch at intel.com>; Yang, York <york.yang at intel.com>
Subject: Mistery of the function: static void enable_rom_caching(void)

Hello community,

I was/got again today in Coreboot directory src/soc/intel/braswell/bootblock/bootblock.c looking at static void enable_rom_caching(void).

Then, since Paul Menzel have announcement ([ANNOUNCEMENT] Support for Intel Kaby Lake), I went to look into src/soc/intel/skylake/bootblock/bootblock.c, but I did not find this function. Kaby Lake patches do not support this function as well.

Then I did the following on my WIN 10 (using VMware workstation 12) VM Fedora 24:

[zoran at localhost intel]$ pwd
/home/zoran/projects/coreboot/coreboot/src/soc/intel
[zoran at localhost intel]$ git describe
4.4-1038-gdd65ef8
[zoran at localhost intel]$ ls -al
total 48
drwxrwxr-x. 12 4096 Aug  1 10:02 .
drwxrwxr-x. 14 4096 Aug  1 10:02 ..
drwxrwxr-x.  5 4096 Aug  1 10:02 apollolake
drwxrwxr-x.  6 4096 Aug  1 10:02 baytrail
drwxrwxr-x.  6 4096 Aug  1 10:02 braswell
drwxrwxr-x.  6 4096 Aug  1 10:02 broadwell
drwxrwxr-x.  3 4096 Aug  1 10:02 common
drwxrwxr-x.  7 4096 Aug  1 10:02 fsp_baytrail
drwxrwxr-x.  7 4096 Aug  1 10:02 fsp_broadwell_de
drwxrwxr-x.  5 4096 Aug  1 10:02 quark
drwxrwxr-x.  3 4096 Aug  1 10:02 sch
drwxrwxr-x.  7 4096 Aug  1 10:02 skylake
[zoran at localhost intel]$ grep -r enable_rom *
baytrail/bootblock/bootblock.c:static void enable_rom_caching(void)
baytrail/bootblock/bootblock.c:          enable_rom_caching();
braswell/bootblock/bootblock.c:static void enable_rom_caching(void)
braswell/bootblock/bootblock.c:         enable_rom_caching();
broadwell/bootblock/cpu.c:static void enable_rom_caching(void)
broadwell/bootblock/cpu.c:     enable_rom_caching();
fsp_baytrail/bootblock/bootblock.c:static void enable_rom_caching(void)
fsp_baytrail/bootblock/bootblock.c:   enable_rom_caching();
[zoran at localhost intel]$

We see here that from skylake (also does not exists in apollolake) this function is dropped.

Any logical explanation for this mismatch?

Thank you,
Zoran

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