Add hw1

hw1/section_a.md

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+---
+title: ECE 371 HW 1
+author: Edith Boles
+---
+
+1. `open()` system call
+
+   A. List the BUGS when using the system call.
+
+      > BUGS
+      >
+      > Currently, it is not possible to enable signal-driven I/O by specifying O_ASYNC when calling open(); use fcntl(2) to enable this flag.
+      >
+      > One must check for two different error codes, EISDIR and ENOENT, when trying to determine whether the kernel supports O_TMPFILE functionality.
+      >
+      > When  both  O_CREAT  and  O_DIRECTORY are specified in flags and the file specified by pathname does not exist, open() will create a regular file (i.e., O_DIRECTORY is ignored).
+
+   B. What files need to be included to use this function?
+      
+      `open` is inside `fcntl.h`.
+
+   C. List the first three related system calls to open().
+
+      ```
+      SEE ALSO
+             chmod(2), chown(2), close(2), ...
+      ```
+
+   D. Choose one of the system calls from above and list its bugs (also list
+      what system call you chose) and files needing to be included to use
+      the system call
+
+      For `link(2)`, you need to include `fcntrl.h` and `unistd.h`. The `BUGS` section details an issue on NFS filesystems that requires verifying the operation before assuming it succeeded. 
+
+2. https://elixir.bootlin.com/, searching on kernel `v6.19.11`
+
+   A. `usb_device` is defined in `include/linux/usb.h`, with first five members being:
+
+      ```
+      int		devnum;
+      char		devpath[16];
+      u32		route;
+      enum usb_device_state	state;
+      enum usb_device_speed	speed;
+      ```
+
+   B. `include/uapi/linux/usb/ch9.h`
+
+   C. ```
+      enum usb_device_speed {
+         USB_SPEED_UNKNOWN = 0,			/* enumerating */
+         USB_SPEED_LOW, USB_SPEED_FULL,		/* usb 1.1 */
+         USB_SPEED_HIGH,				/* usb 2.0 */
+         USB_SPEED_WIRELESS,			/* wireless (usb 2.5) */
+         USB_SPEED_SUPER,			/* usb 3.0 */
+         USB_SPEED_SUPER_PLUS,			/* usb 3.1 */
+      };
+      ```
+