Changeset d5b37b6 in mainline for uspace/lib

Timestamp:

2025-04-17T15:14:03Z (9 months ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master

Children:

690ad20

Parents:

571cc2d

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-11 17:35:09)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2025-04-17 15:14:03)

Message:

Use a new syscall, SYS_KIO_READ, for reading from KIO buffer

Originally, the buffer memory was shared between kernel and
uspace, presumably to avoid the overhead of syscalls.
However, this makes synchronization with kernel impossible,
so it is not possible to ensure it works reliably without
random glitches. Also, relative to everything else /app/kio
does with the data, the syscall overhead is positively tiny.

Location:

uspace/lib/c

Files:

• generic/io/kio.c (modified) (2 diffs)
• include/io/kio.h (modified) (2 diffs)

uspace/lib/c/generic/io/kio.c

@@ -34 +34 @@
  */
 
+#include <abi/syscall.h>
 #include <stddef.h>
 #include <libc.h>
@@ -112 +113 @@
 }
 
+size_t kio_read(char32_t *buf, size_t n, size_t at)
+{
+        return __SYSCALL3(SYS_KIO_READ, (sysarg_t) buf, n, at);
+}
+
 /** Print formatted text to kio.
  *

uspace/lib/c/include/io/kio.h

@@ -36 +36 @@
 #define _LIBC_IO_KIO_H_
 
-#include <stddef.h>
-#include <stdarg.h>
-#include <io/verify.h>
 #include <_bits/errno.h>
 #include <_bits/size_t.h>
+#include <io/verify.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <uchar.h>
 
 extern void __kio_init(void);
@@ -50 +51 @@
     _HELENOS_PRINTF_ATTRIBUTE(1, 2);
 extern int kio_vprintf(const char *, va_list);
+
+extern size_t kio_read(char32_t *buf, size_t n, size_t at);
 
 /*