EA8500 got issue.
branch openwrt-21.02-nss-qsdk11.0 got bootloop with either sysupgrade from official build or factory from stock firmware
branch openwrt-21.02-nss-qsdk10.0 and kernel5.4-nss-qsdk10.0 could flash and boot successful, but PC couldn't access the router's IP, neither DHCP nor static. And through the serial cable I found error during booting stage:
[ 23.250495] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
[ 23.252115] blk_update_request: I/O error, dev mtdblock0, sector 8 op 0x0:(READ) flags 0x80700 phys_seg 3 prio class 0
[ 23.261824] blk_update_request: I/O error, dev mtdblock0, sector 16 op 0x0:(READ) flags 0x80700 phys_seg 2 prio class 0
[ 23.272704] blk_update_request: I/O error, dev mtdblock0, sector 24 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
[ 23.283173] blk_update_request: I/O error, dev mtdblock0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
[ 23.292315] Buffer I/O error on dev mtdblock0, logical block 0, async page read
[ 23.310601] blk_update_request: I/O error, dev mtdblock0, sector 32 op 0x0:(READ) flags 0x80700 phys_seg 8 prio class 0
[ 23.311676] blk_update_request: I/O error, dev mtdblock0, sector 40 op 0x0:(READ) flags 0x80700 phys_seg 7 prio class 0
[ 23.321714] blk_update_request: I/O error, dev mtdblock0, sector 48 op 0x0:(READ) flags 0x80700 phys_seg 6 prio class 0
[ 23.332458] blk_update_request: I/O error, dev mtdblock0, sector 56 op 0x0:(READ) flags 0x80700 phys_seg 5 prio class 0
[ 23.343217] blk_update_request: I/O error, dev mtdblock0, sector 64 op 0x0:(READ) flags 0x80700 phys_seg 4 prio class 0
[ 23.357077] Buffer I/O error on dev mtdblock0, logical block 1, async page read
[ 23.368446] Buffer I/O error on dev mtdblock1, logical block 0, async page read
[ 23.379165] Buffer I/O error on dev mtdblock1, logical block 1, async page read
[ 23.632210] Buffer I/O error on dev mtdblock2, logical block 0, async page read
[ 23.641850] Buffer I/O error on dev mtdblock2, logical block 1, async page read
[ 23.647224] Buffer I/O error on dev mtdblock3, logical block 0, async page read
[ 23.650937] Buffer I/O error on dev mtdblock3, logical block 0, async page read
[ 23.660385] Buffer I/O error on dev mtdblock4, logical block 0, async page read
[ 23.672981] Buffer I/O error on dev mtdblock4, logical block 0, async page read