From 226f51c7651d3ece93b2fcc141d791b6ad00fa18 Mon Sep 17 00:00:00 2001 From: Jeremy Compostella Date: Thu, 12 Oct 2023 09:40:12 -0700 Subject: x86: Add ramstage CBFS cache scratchpad support Having a CBFS cache scratchpad offers a generic way to decompress CBFS files through the cbfs_map() function without having to reserve a per-file specific memory region. This commit introduces the x86 `RAMSTAGE_CBFS_CACHE_SIZE' Kconfig to set a ramstage CBFS cache size. A cache size of zero disables the CBFS cache feature. The default size is 16 KB which seems a reasonable minimal value large enough to satisfy basic needs such as the decompression of a small configuration file. This setting can be adjusted depending on the platform needs and capabilities. To support S3 suspend/resume use-case, the CBFS cache memory cannot be released to the operating system. There are two options to meet this requirement: 1. Define a static CBFS cache buffer (located in the .bss section) 2. Create a new CBMEM entry Option #2 seems more powerful but considering that: 1. The CBFS cache is actually not a cache but just a scratch pad designed to be isolated between stages 2. postcar is a very short stage not really needing CBFS cache 3. The static initialization of the `cbfs_cache' global variable (cf. src/lib/cbfs.c) offers a simple and robust design => It is simpler to use a static buffer and limit the support to ramstage. Since some AMD SoCs (cf. `SOC_AMD_COMMON_BLOCK_NONCAR' Kconfig) define a `_cbfs_cache' region, an extra `POSTRAM_CBFS_CACHE_IN_BSS' Kconfig must be set to enable the use of a static buffer as the CBFS cache scratchpad. TEST=Decompression of vbt.bin in ramstage on rex using cbfs_map() Change-Id: I7fbb1b51cda9f84842992e365b16c5ced1010b89 Signed-off-by: Jeremy Compostella Reviewed-on: https://review.coreboot.org/c/coreboot/+/77885 Reviewed-by: Arthur Heymans Tested-by: build bot (Jenkins) --- src/arch/x86/Kconfig | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'src/arch/x86/Kconfig') diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig index b0e479b1c4..90ece988c0 100644 --- a/src/arch/x86/Kconfig +++ b/src/arch/x86/Kconfig @@ -160,6 +160,23 @@ config PRERAM_CBFS_CACHE_SIZE Define the size of the Pre-RAM stages CBFS cache. A size of zero disables the CBFS cache feature in pre-memory stages. +config POSTRAM_CBFS_CACHE_IN_BSS + bool + default y if !SOC_AMD_COMMON_BLOCK_NONCAR + help + Allocate the post-memory CBFS cache scratchpad in the .bss + section. CBFS cache will rely on a simple static C buffer + while traditionally CBFS cache memory region is reserved in + the device memory layout. + +config RAMSTAGE_CBFS_CACHE_SIZE + hex + default 0x4000 + depends on POSTRAM_CBFS_CACHE_IN_BSS + help + Define the size of the ramstage CBFS cache. A size of zero + disables the CBFS cache feature in ramstage. + config PC80_SYSTEM bool default y if ARCH_X86 -- cgit v1.2.3