xiaoxiang781216 commented on code in PR #8000:
URL: https://github.com/apache/nuttx/pull/8000#discussion_r1059388062
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include/nuttx/fs/fs.h:
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@@ -206,16 +207,21 @@ struct file_operations
* treated like unions.
*/
- int (*close)(FAR struct file *filep);
- ssize_t (*read)(FAR struct file *filep, FAR char *buffer, size_t buflen);
- ssize_t (*write)(FAR struct file *filep, FAR const char *buffer,
- size_t buflen);
- off_t (*seek)(FAR struct file *filep, off_t offset, int whence);
- int (*ioctl)(FAR struct file *filep, int cmd, unsigned long arg);
+ int (*close)(FAR struct file *filep);
+ ssize_t (*read)(FAR struct file *filep, FAR char *buffer, size_t buflen);
+ ssize_t (*write)(FAR struct file *filep, FAR const char *buffer,
+ size_t buflen);
+ off_t (*seek)(FAR struct file *filep, off_t offset, int whence);
+ int (*ioctl)(FAR struct file *filep, int cmd, unsigned long arg);
+ int (*truncate)(FAR struct file *filep, off_t length);
+ FAR void *(*mmap)(FAR struct file *filep, off_t start, size_t length);
+ int (*munmap)(FAR struct task_group_s *group, FAR struct inode *inode,
Review Comment:
> Yes, we use an implementation of a linked list, stored into the group,
which we call "vm_map". I offered an earlier version of this some months ago.
When the interfaces for these settle, I can come back to that and offer the
"full" unmap solution in another PR.
>
> IMHO, we shouldn't try to copy linux too much. There everything can be
buffered/file system cached, and the implementation relies on having full
virtual memory management. Although it is great for general purpose OS, I don't
think that it is feasible at this point to try to do all of that for NuttX.
Instead, let's concentrate for basic needs and keep NuttX as a real-time os :)
Yes, I agree that we just need learn the core design principle from Linux,
but the detail and implementation may difference dramatically.
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