I tried to config the 8051 project and found a problem after disassembler the code.
There are some library link in the code such as libsdcc.lib (startup.rel).
After reset the program call a few thing and then jump to 0x03 and then long jump to address 0x62.
which the start of (Main)
I have yet found clear ram or set stack pointer assembly code from startup.rel
By the way , the example code (dht11 sdcc toolchian) from remote repository found the same problem.
I insert hex code as here after.
:03000000020006F5
:03005F0002000399
:0300030002006296
:1000620053A87F1200C21200C1120087120094121C
:10007200009E1200B443A88012007F80FE75080023
:10008200223205083275A65575A70075A40043A84B
:100092002022759A00759900759B002275CB2075F8
:1000A200CAC075CF0175CEF375CD0375CCE743CBCE
:1000B200802275968075890175898143AB0422225D
:1000C20075A0FF75DC0075D20075800075B1FF75F3
:1000D200DD0075D30075880075B9FF75DE0075D433
:1000E2000075900075C1FF75DE0075D5007594002E
:1000F20075980075C9FF75E20075D6007595007593
:10010200A00075D1FF75E30075D70075B00075D9F1
:10011200FF75E40075DA0075C00075E1FF75E50052
:1001220075DB0075920075E90F75EAF075EB3F75A6
:10013200E60175E72075ED0075EE0075EF0075ECD0
:050142000075ACFF2276
:06003500E4787FF6D8FD1F
:100013007900E94400601B7A0090014B780175A0D8
:1000230000E493F2A308B8000205A0D9F4DAF2754C
:02003300A0FF2C
:10003B007800E84400600A790175A000E4F309D860
:10004B00FC7800E84400600C7900900001E4F0A318
:04005B00D8FCD9FAFA
:0D000600758108120147E5826003020003C6
:04014700758200229B
:00000001FF