From mboxrd@z Thu Jan 1 00:00:00 1970 From: xerofoify@gmail.com (nick) Date: Sun, 19 Apr 2015 16:51:08 -0400 Subject: Question about assembly in set bit function for x86 architecture Message-ID: <5534153C.4070303@gmail.com> To: kernelnewbies@lists.kernelnewbies.org List-Id: kernelnewbies.lists.kernelnewbies.org Greetings All, I am wondering what the below code in the asm modifier does: static inline void set_bit(int nr, void *addr) { asm("btsl %1,%0" : "+m" (*(u32 *)addr) : "Ir" (nr)); } This would be very helpful as I am new to x86 assembly and don't even known what register(s)/instruction(s) this touches and therefore this is impossible for me to look up in the Intel Manuals. If someone either tells me the registers/instructions this uses or explains the code that would be very helpful. Nick