Hello,

I got the following output via RS232 console:
------------------------------------------------------------------------------
coreboot-4.9-539-gde3ace0-dirty Mon Jan 28 13:44:10 UTC 2019 romstage starting (log level: 7)...
RTC Init
Starting the Intel FSP (early_init)
CBFS: 'Master Header Locator' located CBFS at [200:200000)
CBFS: Locating 'cpu_microcode_blob.bin'
CBFS: Found @ offset 7940 size cc00
microcode: sig=0x30679 pf=0x1 revision=0x90a
PM1_STS = 0x2100 PM1_CNT = 0x0 GEN_PMCON1 = 0x45008
prev_sleep_state = S5
Configure Default UPD Data
PcdMrcInitSPDAddr1:             0xa0 (default)
PcdMrcInitSPDAddr2:             0xa2 (default)
PcdSataMode:            0x01 (set)
PcdLpssSioEnablePciMode:                0x01 (default)
PcdMrcInitMmioSize:             0x800 (default)
PcdIgdDvmt50PreAlloc:           0x02 (default)
PcdApertureSize:                0x02 (default)
PcdGttSize:             0x02 (default)
SerialDebugPortAddress:         0x3f8 (default)
SerialDebugPortType:            0x01 (default)
PcdMrcDebugMsg:         0x00 (default)
PcdSccEnablePciMode:            0x01 (default)
IgdRenderStandby:               0x00 (default)
TxeUmaEnable:           0x00 (default)
PcdOsSelection:         0x04 (default)
PcdEMMC45DDR50Enabled:          0x01 (default)
PcdEMMC45HS200Enabled:          0x00 (default)
PcdEMMC45RetuneTimerValue:              0x08 (default)
PcdEnableIgd:           0x01 (default)
AutoSelfRefreshEnable:          0x00 (default)
APTaskTimeoutCnt:               0x00 (default)
GTT Size:               2 MB
Tseg Size:              8 MB
Aperture Size:          256 MB
IGD Memory Size:        64 MB
MMIO Size:              2048 MB
MIPI/ISP:               Disabled
Sdio:                   Enabled
Sdcard:                 Enabled
SATA:                   Enabled
SIO Dma 0:              Enabled
SIO I2C0:               Enabled
SIO I2C1:               Enabled
SIO I2C2:               Enabled
SIO I2C3:               Enabled
SIO I2C4:               Enabled
SIO I2C5:               Enabled
SIO I2C6:               Enabled
Azalia:                 Enabled
SIO Dma1:               Enabled
Pwm0:                   Enabled
Pwm1:                   Enabled
Hsuart0:                Enabled
Hsuart1:                Enabled
Spi:                    Enabled
Lpe:                    Disabled
eMMC Mode:              eMMC 4.5
SATA Mode:              AHCI
Xhci:                   Enabled
-----------------------------------------------------------------------------------------
And then - nothing. 
It seems payload is not running.
Currently SeaBIOS is enabled. 

My goal it to boot vanilla linux with grub (or grub2) via RS232 console only. 
With the original BIOS I got from vendor, I used knoppix to burn grub on the SATA disk. 
If coreboot is running grub, how should I burn grub ? Is it part of coreboot image ?

Thank you,
Zvika