[PATCH 1/2] console: scale number of log messages with available RAM

[Ahmad Fatoum]

The default value of 1000 messages is too small with
CONFIG_COMPILE_LOGLEVEL=7, because the many driver debug messages
will evict any earlier error or warning messages that have been
in the log.

Assuming a log record size of 128 bytes, 1000 messages translates to
128kB, which has quite a bit of breathing room. Let's instead scale the
maximum with the available memory: one message per 32KiB of malloc area.

This gives us:

  -  64M total memory ->  ~32M malloc area ->  1K messages (128K bytes)
  - 256M total memory -> ~128M malloc area ->  4K messages (512K bytes)
  -   1G total memory -> ~512M malloc area -> 16K messages (  2M bytes)

Users for which this is too excessive can still configure this via the
environment.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 common/console_common.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/common/console_common.c b/common/console_common.c
index c78581299248..d25fb0dc5dde 100644
--- a/common/console_common.c
+++ b/common/console_common.c
@@ -14,12 +14,14 @@
 #include <environment.h>
 #include <globalvar.h>
 #include <magicvar.h>
+#include <memory.h>
 #include <of.h>
 #include <password.h>
 #include <clock.h>
 #include <malloc.h>
 #include <linux/pstore.h>
 #include <linux/math64.h>
+#include <linux/sizes.h>
 #include <linux/overflow.h>
 
 #ifndef CONFIG_CONSOLE_NONE
@@ -37,7 +39,7 @@ int barebox_loglevel = CONFIG_DEFAULT_LOGLEVEL;
 
 LIST_HEAD(barebox_logbuf);
 static int barebox_logbuf_num_messages;
-static int barebox_log_max_messages = 1000;
+static int barebox_log_max_messages;
 
 static void log_del(struct log_entry *log)
 {
@@ -173,15 +175,18 @@ bool console_allow_color(void)
 
 static int console_common_init(void)
 {
-	if (IS_ENABLED(CONFIG_LOGBUF))
+	if (IS_ENABLED(CONFIG_LOGBUF)) {
+		barebox_log_max_messages
+			= clamp(mem_malloc_size() / SZ_32K, 1000UL, 100000UL);
 		globalvar_add_simple_int("log_max_messages",
 				&barebox_log_max_messages, "%d");
+	}
 
 	globalvar_add_simple_bool("allow_color", &__console_allow_color);
 
 	return globalvar_add_simple_int("loglevel", &barebox_loglevel, "%d");
 }
-device_initcall(console_common_init);
+core_initcall(console_common_init);
 
 int log_writefile(const char *filepath)
 {
-- 
2.39.2