[coreboot-gerrit] [M] Change in coreboot[main]: acpi: Add support for DHRD size reporting

[Shuo Liu (Code Review)]

Attention is currently required from: Angel Pons, Arthur Heymans, Chen, Gang C, Christian Walter, Cliff Huang, Dinesh Gehlot, Eran Mitrani, Jakub Czapiga, Jeff Daly, Jincheng Li, Johnny Lin, Jonathan Zhang, Kapil Porwal, Lance Zhao, Lean Sheng Tan, Nick Vaccaro, Nico Huber, Patrick Rudolph, Paul Menzel, Sean Rhodes, Subrata Banik, Tarun, Tim Chu, Tim Wawrzynczak, Vanessa Eusebio, Werner Zeh.

Shuo Liu has posted comments on this change by Shuo Liu. ( https://review.coreboot.org/c/coreboot/+/82429?usp=email )

Change subject: acpi: Add support for DHRD size reporting
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Patch Set 15:

(3 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/82429/comment/adbd8c1b_7ea04d87?usp... :
PS15, Line 11: the register set is 2^N 4 KB pages.
> If the value of N is zero, what happens? I didn't find an answer in the VT-d spec (`D51397-016`).

When N is zero, the size would be 2^0 4KB pages, a.k.a. 1 * 4KB page, which is as the case of the previous spec not specifying the size and 4KB page is used by default.

File src/acpi/acpi_dmar.c:

https://review.coreboot.org/c/coreboot/+/82429/comment/a6f51724_87e13469?usp... :
PS15, Line 50: 	drhd->bar = bar;
> VT-d spec (`D51397-016`) says: […]

Good catch, we need an assert here.

https://review.coreboot.org/c/coreboot/+/82429/comment/5c5d9fb1_6a556533?usp... :
PS15, Line 51: drhd->size = log2(size) - 12;
             : 	/*
             : 	 * Refer to chapter 8.3 of https://cdrdv2.intel.com/v1/dl/getContent/671081
             : 	 * only bit 3:0 are allowed to be used
             : 	 */
             : 	assert(!(drhd->size >> 4));
> Although this check is correct, I find it rather convoluted. How about: […]

Fix applied.