ok, I think I made some progress: usrApp starts on openWrt! 
it did need the dev/mem device and it does talk to /dev/spiXXXXX device too (confirmed by strace)
root@OpenWrt:/mnt# ./usrApp
RTK User Space SDK Initialize
RTCORE Driver Module Initialize
IOAL init
IOAL init
Log init
Hardware-profile probe (RTL9303_8XGE)
Hardware-profile init
IOAL init
IOAL init
RTK Driver Module Initialize
MAC probe (unit 0)
Chip 9303 (found)
MAC init (unit 0)
PHY probe (unit 0)
Chip Construct (unit 0)
Chip Construct
Disable PHY Polling
PHY Reset
MAC Construct
Turn Off Serdes
Serdes Construct
PHY Construct
Turn On Serdes
Mac_Polling_PHY Config
Enable PHY Polling
Misc
PHY init (unit 0)
Mgmt_dev init (unit 0)
unit=0,sds=3 cali success.
failed to connect to ubus
Start to run Diag Shell....
RTK.0> sh: /sbin/exec-dir: not found
unexpected switch port:27, link status:1
sh: /sbin/exec-dir: not found
and running the sys dump hwp all gives similar result as on oem firmware (but starts throwing a lot of noise at the end)
RTK.0> sys dump hwp all
Profile Information (67D678):
Profile-Name: RTL9303_8XGE
Profile-ID: 9300015
Profile-ID-Type: 0
CPU Type: External
SW Desc IDX: 0
Slave Interrupt Pin: 255
Chip count: 1
Cascade Mode: No
unit 0, 9303(1) (cpu)
swcore support: 1
swcore-CPU Interface(1:normal, 2:SPI, 3: PCIe): 2
nic support: 1
port count: 6
macId: 8,20,24,25,27,28,
CpuMacId: 28 (attr)
Ether cnt: 5, macId(m/M): 8/27 msk:0x0b100100 0x00000000 (A)
Uplink cnt: 3, macId(m/M):24/27 msk:0x0b000000 0x00000000 (A)
2_5GE cnt: 3, macId(m/M): 0/25 msk:0x03100000 0x00000000 (E)
XGE cnt: 2, macId(m/M): 8/27 msk:0x08000100 0x00000000 (E)
Copper cnt: 4, macId(m/M): 8/25 msk:0x03100100 0x00000000 (M)
Serdes cnt: 1, macId(m/M):27/27 msk:0x08000000 0x00000000 (M)
port: 8, phyIdx0
port:20, phyIdx1
port:24, phyIdx2
port:25, phyIdx3
port:27, phyIdx255
port:28, phyIdx255
PHY Count:4
type:25(CUST5 ) port:1 baseMac:8
type:19(RTL8226B ) port:1 baseMac:20
type:19(RTL8226B ) port:1 baseMac:24
type:24(CUST4 ) port:1 baseMac:25
PHY[0]: chipID 25, baseMacId 8, phy_max 1
PHY[1]: chipID 19, baseMacId 20, phy_max 1
PHY[2]: chipID 19, baseMacId 24, phy_max 1
PHY[3]: chipID 24, baseMacId 25, phy_max 1
unitMapStruct[0].pUnitInfo:9034a038,parsed_info=9034a020,swDescp=67d6d8
unitMapStruct[1].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[2].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[3].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[4].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[5].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[6].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[7].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[8].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[9].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[10].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[11].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[12].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[13].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[14].pUnitInfo:820088,parsed_info=0,swDescp=0
unitMapStruct[15].pUnitInfo:820088,parsed_info=0,swDescp=0
(&parsedInfoEmpty.unitInfo[EMPTY]=820088)
info->hwp=RTL9303_8XGE(67d678)
info->hwp_localUnitCnt=1
info->hwp_embeddedCpuUnitId=0
info->hwp_cascade_mode=0
info->hwp_cascadeSlaveUnitID=0
info->hwp->swDescp[0]=67d6d8
info->hwp->swDescp[1]=0
info->hwp->swDescp[2]=0
info->unitInfo[0].hwp_chip_id=93030000
info->unitInfo[0].hwp_chip_revision=1
info->unitInfo[0].hwp_chip_family_id=93000000
info->unitInfo[0].hwp_maxMacId=28
info->unitInfo[0].hwp_minMacId=8
info->unitInfo[0].hwp_macID2PortDescp:
p[0]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[1]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[2]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[3]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[4]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[5]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[6]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[7]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[8]=67d6ec,mac_id=8,phyIdx=0,sdsIdx=0,smi=2,phy_addr=0,attr=1,eth=8,medi=1,
p[9]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[10]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[11]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[12]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[13]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[14]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[15]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[16]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[17]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[18]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[19]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[20]=67d6fc,mac_id=20,phyIdx=1,sdsIdx=1,smi=0,phy_addr=7,attr=1,eth=4,medi=1,
p[21]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[22]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[23]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[24]=67d70c,mac_id=24,phyIdx=2,sdsIdx=2,smi=1,phy_addr=3,attr=3,eth=4,medi=1,
p[25]=67d71c,mac_id=25,phyIdx=3,sdsIdx=3,smi=0,phy_addr=15,attr=3,eth=4,medi=1,
p[26]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[27]=67d72c,mac_id=27,phyIdx=255,sdsIdx=4,smi=255,phy_addr=255,attr=3,eth=8,medi=8,
p[28]=67d73c,mac_id=28,phyIdx=255,sdsIdx=255,smi=255,phy_addr=255,attr=8,eth=255,medi=255,
p[29]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[30]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[31]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[32]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[33]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[34]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[35]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[36]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[37]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[38]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[39]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[40]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[41]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[42]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[43]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[44]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[45]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[46]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[47]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[48]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[49]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[50]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[51]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[52]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[53]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[54]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[55]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[56]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[57]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[58]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[59]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[60]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[61]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[62]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
p[63]=822148,mac_id=0,phyIdx=0,sdsIdx=0,smi=0,phy_addr=0,attr=0,eth=0,medi=0,
info->unitInfo[0].hwp_macID2SerdesID:
p[0]=255,p[1]=255,p[2]=255,p[3]=255,p[4]=255,p[5]=255,p[6]=255,p[7]=255,p[8]=3,p[9]=255,p[10]=255,p[11]=255,p[12]=255,p[13]=255,p[14]=255,p[15]=255,p[16]=255,p[17]=255,p[18]=255,p[19]=255,p[20]=5,p[21]=255,p[22]=255,p[23]=255,p[24]=6,p[25]=7,p[26]=255,p[27]=9,p[28]=255,p[29]=255,p[30]=255,p[31]=255,p[32]=255,p[33]=255,p[34]=255,p[35]=255,p[36]=255,p[37]=255,p[38]=255,p[39]=255,p[40]=255,p[41]=255,p[42]=255,p[43]=255,p[44]=255,p[45]=255,p[46]=255,p[47]=255,p[48]=255,p[49]=255,p[50]=255,p[51]=255,p[52]=255,p[53]=255,p[54]=255,p[55]=255,p[56]=255,p[57]=255,p[58]=255,p[59]=255,p[60]=255,p[61]=255,p[62]=255,p[63]=255,
info->unitInfo[0].hwp_portCpuMacId=28
Ether : count=5, max=27, min=8
Uplink : count=3, max=27, min=24
Cascade: count=0, max=0, min=64
Fe : count=0, max=0, min=64
Ge : count=0, max=0, min=64
Xge : count=2, max=27, min=8
SXge : count=0, max=0, min=64
Copper : count=4, max=25, min=8
Fiber : count=0, max=0, min=64
Combo : count=0, max=0, min=64
Serdes : count=1, max=27, min=27
info->unitInfo[0].hwp_sdsID2phyType:
SDS 3 PHY:25
SDS 5 PHY:19
SDS 6 PHY:19
SDS 7 PHY:24
SDS 9 PHY:20
info->unitInfo[0].hwp_sdsID2MacID:
s[3]=8,s[5]=20,s[6]=24,s[7]=25,s[9]=27,
info->unitInfo[0].hwp_attriPortMask:
attr[0]=b100100
attr[0]=0
attr[1]=b000000
attr[1]=0
attr[2]=0
attr[2]=0
attr[3]=10000000
attr[3]=0
attr[4]=0
attr[4]=0
info->unitInfo[0].hwp_ethTypePortMask:
eth[0]=0
eth[0]=0
eth[1]=0
eth[1]=0
eth[2]=3100000
eth[2]=0
eth[3]=8000100
eth[3]=0
eth[4]=0
eth[4]=0
info->unitInfo[0].hwp_mediumPortMask:
med[0]=3100100
med[0]=0
med[1]=0
med[1]=0
med[2]=0
med[2]=0
med[3]=8000000
med[3]=0
info->unitInfo[0].hwp_allPortMask=1b100100
info->unitInfo[0].hwp_allPortMask=0
info->unitInfo[0].hwp_macID2phyAddr:
p[0]=255,p[1]=255,p[2]=255,p[3]=255,p[4]=255,p[5]=255,p[6]=255,p[7]=255,p[8]=0,p[9]=255,p[10]=255,p[11]=255,p[12]=255,p[13]=255,p[14]=255,p[15]=255,p[16]=255,p[17]=255,p[18]=255,p[19]=255,p[20]=7,p[21]=255,p[22]=255,p[23]=255,p[24]=3,p[25]=15,p[26]=255,p[27]=255,p[28]=255,p[29]=255,p[30]=255,p[31]=255,p[32]=255,p[33]=255,p[34]=255,p[35]=255,p[36]=255,p[37]=255,p[38]=255,p[39]=255,p[40]=255,p[41]=255,p[42]=255,p[43]=255,p[44]=255,p[45]=255,p[46]=255,p[47]=255,p[48]=255,p[49]=255,p[50]=255,p[51]=255,p[52]=255,p[53]=255,p[54]=255,p[55]=255,p[56]=255,p[57]=255,p[58]=255,p[59]=255,p[60]=255,p[61]=255,p[62]=255,p[63]=255,
info->unitInfo[0].hwp_macID2phyType:
p[0]=27,p[1]=27,p[2]=27,p[3]=27,p[4]=27,p[5]=27,p[6]=27,p[7]=27,p[8]=25,p[9]=27,p[10]=27,p[11]=27,p[12]=27,p[13]=27,p[14]=27,p[15]=27,p[16]=27,p[17]=27,p[18]=27,p[19]=27,p[20]=19,p[21]=27,p[22]=27,p[23]=27,p[24]=19,p[25]=24,p[26]=27,p[27]=20,p[28]=20,p[29]=27,p[30]=27,p[31]=27,p[32]=27,p[33]=27,p[34]=27,p[35]=27,p[36]=27,p[37]=27,p[38]=27,p[39]=27,p[40]=27,p[41]=27,p[42]=27,p[43]=27,p[44]=27,p[45]=27,p[46]=27,p[47]=27,p[48]=27,p[49]=27,p[50]=27,p[51]=27,p[52]=27,p[53]=27,p[54]=27,p[55]=27,p[56]=27,p[57]=27,p[58]=27,p[59]=27,p[60]=27,p[61]=27,p[62]=27,p[63]=27,
info->unitInfo[0].hwp_sdsID2SerdesDescp:
sds[0]=820068,sds[1]=820068,sds[2]=820068,sds[3]=67daed,sds[4]=820068,sds[5]=67daef,sds[6]=67daf1,sds[7]=67daf3,sds[8]=820068,sds[9]=67daf5,sds[10]=820068,sds[11]=820068,sds[12]=820068,sds[13]=820068,sds[14]=820068,sds[15]=820068,sds[16]=820068,sds[17]=820068,sds[18]=820068,sds[19]=820068,sds[20]=820068,sds[21]=820068,sds[22]=820068,sds[23]=820068,
info->unitInfo[0].hwp_phyBaseMacID:
p[0]=255,p[1]=255,p[2]=255,p[3]=255,p[4]=255,p[5]=255,p[6]=255,p[7]=255,p[8]=8,p[9]=255,p[10]=255,p[11]=255,p[12]=255,p[13]=255,p[14]=255,p[15]=255,p[16]=255,p[17]=255,p[18]=255,p[19]=255,p[20]=20,p[21]=255,p[22]=255,p[23]=255,p[24]=24,p[25]=25,p[26]=255,p[27]=27,p[28]=28,p[29]=255,p[30]=255,p[31]=255,p[32]=255,p[33]=255,p[34]=255,p[35]=255,p[36]=255,p[37]=255,p[38]=255,p[39]=255,p[40]=255,p[41]=255,p[42]=255,p[43]=255,p[44]=255,p[45]=255,p[46]=255,p[47]=255,p[48]=255,p[49]=255,p[50]=255,p[51]=255,p[52]=255,p[53]=255,p[54]=255,p[55]=255,p[56]=255,p[57]=255,p[58]=255,p[59]=255,p[60]=255,p[61]=255,p[62]=255,p[63]=255,
info->unitInfo[0].hwp_ledNum:
p[0]=0,p[1]=0,p[2]=0,p[3]=0,p[4]=0,p[5]=0,p[6]=0,p[7]=0,p[8]=2,p[9]=0,p[10]=0,p[11]=0,p[12]=0,p[13]=0,p[14]=0,p[15]=0,p[16]=0,p[17]=0,p[18]=0,p[19]=0,p[20]=2,p[21]=0,p[22]=0,p[23]=0,p[24]=2,p[25]=2,p[26]=0,p[27]=2,p[28]=255,p[29]=0,p[30]=0,p[31]=0,p[32]=0,p[33]=0,p[34]=0,p[35]=0,p[36]=0,p[37]=0,p[38]=0,p[39]=0,p[40]=0,p[41]=0,p[42]=0,p[43]=0,p[44]=0,p[45]=0,p[46]=0,p[47]=0,p[48]=0,p[49]=0,p[50]=0,p[51]=0,p[52]=0,p[53]=0,p[54]=0,p[55]=0,p[56]=0,p[57]=0,p[58]=0,p[59]=0,p[60]=0,p[61]=0,p[62]=0,p[63]=0,
info->unitInfo[0].hwp_multiSdsPortSdsmask:
info->unitInfo[0].hwp_multiSdsBaseSds:
info->unitInfo[0].hwp_macID2SCDescp:
info->unitInfo[0].hwp_scBaseMacID:
info->unitInfo[0].swDescp=67d6d8
info->unitInfo[0].parsed_info=9034a020