Loaders · Loader Design Options

1. Build the starter
   gcc -Wall -o sicload sicload_starter.c then ./sicload count.obj. Memory is all xx: nothing is loaded yet.
2. TODO 1: load_T
   Copy the bytes of a T record into memory. ./sicload count.obj | diff - expected_abs.txt must print nothing.
3. TODO 2: patch
   Add delta to a field of 4, 5 or 6 half-bytes, keeping the other bits. Test by hand: 100000 + 4011 → 104011.
4. TODO 3: M records
   One line in load_one. Then ./sicload -v -x -r 5000 count0.obj: TOTAL must become 000003.
5. Try other addresses
   Load count0.obj at 0, 1234 and 7000 with -x. Same result every time? Then your relocation is right.
6. C side
   In the demo folder: nm, readelf -r and objdump -d on main.o, then link with -Wl,-Map and find the call to counta.

Extra: TODO 6 loads bit-mask records (-b 5000 count0_mask.obj). Submit: sicload.c and the output of task 4.

1. TODO 4: Pass 1
   Fill ESTAB from H and D records. ./sicload -l 4000 main.obj counta.obj data.obj must print the load map of Lecture 5.1.
2. TODO 5: Pass 2
   Apply M records with ±symbol from ESTAB. diff your output with expected_link4000.txt: nothing.
3. Errors
   Leave out data.obj, then give data.obj twice. You must get "undefined external symbol TOTAL" and "duplicate external symbol DATA".
4. Libraries
   In demo/: build libcount.a and libcount.so; reproduce the -l order error and the 'cannot open shared object file' error, and fix both.
5. Watch ld.so
   Run with LD_DEBUG=libs and LD_DEBUG=bindings, and with strace. Find where libcount.so is opened and mapped.
6. The GOT
   gdb -batch -x got.gdb ./lazy: write down GOT[counta] before and after the first call; check base + 10f9.

Submit: sicload.c, your load map, and a short report with the GOT values from task 6.