Hi community,
I'm trying to get coreboot running on a Braswell CPU but it hangs when updating the microcode. I'm stuck in bootblock before CAR and could pin down the problem to the intel_microcode_load_unlocked function in src/cpu/intel/microcode.c where coreboot writes the microcode base address to the IA32_BIOS_UPDT_TRIG register (0x79).
outb(0xF7, 0x80);
msr.lo = (unsigned long)m + sizeof(struct microcode); msr.hi = 0; wrmsr(0x79, msr); outb(0xF8, 0x80);
The outb calls have been added by me, and F7 is just the last post code I see, a few seconds before the CPU reboots. It never reaches F8. So I checked the microcode that I've received from Intel and everything seems fine. The microcode signature matches the CPUID, the platform flags match, the checksum correctly yields to zero, and the base address is aligned on a 16-byte boundary. Some checks are also done by coreboot at runtime. I just can't figure out what the problem is here.
Some more Info:
$ build/cbfstool build/coreboot.rom print Performing operation on 'COREBOOT' region... Name Offset Type Size cbfs master header 0x0 cbfs header 32 fallback/romstage 0x80 stage 30660 fallback/ramstage 0x78c0 stage 63482 fallback/payload 0x17100 payload 61118 config 0x26000 raw 439 revision 0x26200 raw 575 cmos_layout.bin 0x26480 cmos_layout 1128 fallback/dsdt.aml 0x26940 raw 17603 payload_config 0x2ae80 raw 1563 payload_revision 0x2b500 raw 233 (empty) 0x2b640 null 248856 cpu_microcode_blob.bin 0x68280 microcode 68608 (empty) 0x78f00 null 683928 fsp.bin 0x11fec0 fsp 296960 (empty) 0x168700 null 489368 mrc.cache 0x1dfec0 mrc_cache 65536 (empty) 0x1eff00 null 63960 bootblock 0x1ff900 bootblock 1424
$ cat ".config" | grep "MICROCODE" # CONFIG_USES_MICROCODE_HEADER_FILES is not set CONFIG_CPU_MICROCODE_CBFS_GENERATE=y # CONFIG_CPU_MICROCODE_CBFS_EXTERNAL_HEADER is not set # CONFIG_CPU_MICROCODE_CBFS_NONE is not set # CONFIG_CPU_MICROCODE_MULTIPLE_FILES is not set CONFIG_CPU_MICROCODE_CBFS_LEN=0x10C00 CONFIG_CPU_MICROCODE_CBFS_LOC=0xFFE68400 # CONFIG_HAVE_ROMSTAGE_MICROCODE_CBFS_SPINLOCK is not set
I really appreciate any hints.
Alex