Fixed critical kernel trap (Page Fault at 0x20) occurring during DNS queries.
Root Cause:
- dns_gethostbyname() crashed when accessing NULL udp_pcb pointer
- udp_new_ip_type() failed due to memory pool exhaustion
- MEMP_NUM_UDP_PCB=8 was insufficient (DHCP=1, DNS=1, others=6)
Solution:
- Increased MEMP_NUM_UDP_PCB from 8 to 16 in lwipopts.h
- Added DNS initialization check function in net_glue.nim
- Documented root cause analysis in DNS_NULL_CRASH_RCA.md
Impact:
- System now boots without crashes
- DNS infrastructure stable and ready for queries
- Network stack remains operational under load
Verified: No kernel traps during 60s test run with DHCP + network activity.
Next: Debug DNS query resolution (separate from crash fix).
9eba865099