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lib: sbi: Introduce an early console buffer for caching early prints 

The console device is registered by platform only in early_init()
callback so any prints before this point will be lost. Introduce an
early console buffer for caching prints before platform early_init().

For crashes before platform early_init(), users can simply dump the
contents of the console_early_buffer[] string using a debugger. The
relative address of the console_early_buffer[] string can be found
using following two commands:

CONSOLE_EARLY_FIFO_ADDR=`${CROSS_COMPILE}objdump -D \
build/platform/generic/firmware/fw_dynamic.elf | \
grep "<console_early_fifo>:" | awk '{print $1}'`

${CROSS_COMPILE}objdump -R build/platform/generic/firmware/fw_dynamic.elf | \
grep $CONSOLE_EARLY_FIFO_ADDR | awk '{print $3}'

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-By: Himanshu Chauhan <hchauhan@ventanamicro.com>
This commit is contained in:
Anup Patel 2024-07-05 10:04:12 +05:30 committed by Anup Patel
parent d35c76a766
commit bb7267a07f
2 changed files with 32 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/sbi/Kconfig
View File

@ -1,6 +1,10 @@
# SPDX-License-Identifier: BSD-2-Clause
menu "SBI Extension Support"
menu "Generic SBI Support"
config CONSOLE_EARLY_BUFFER_SIZE
int "Early console buffer size (bytes)"
default 256
config SBI_ECALL_TIME
bool "Timer extension"

27
lib/sbi/sbi_console.c
View File

@ -9,6 +9,7 @@
#include <sbi/riscv_locks.h>
#include <sbi/sbi_console.h>
#include <sbi/sbi_fifo.h>
#include <sbi/sbi_hart.h>
#include <sbi/sbi_platform.h>
#include <sbi/sbi_scratch.h>
@ -21,6 +22,15 @@ static char console_tbuf[CONSOLE_TBUF_MAX];
static u32 console_tbuf_len;
static spinlock_t console_out_lock = SPIN_LOCK_INITIALIZER;
#ifdef CONFIG_CONSOLE_EARLY_BUFFER_SIZE
#define CONSOLE_EARLY_BUFFER_SIZE CONFIG_CONSOLE_EARLY_BUFFER_SIZE
#else
#define CONSOLE_EARLY_BUFFER_SIZE 256
#endif
static char console_early_buffer[CONSOLE_EARLY_BUFFER_SIZE] = { 0 };
static SBI_FIFO_DEFINE(console_early_fifo, console_early_buffer, \
CONSOLE_EARLY_BUFFER_SIZE, sizeof(char));
bool sbi_isprintable(char c)
{
if (((31 < c) && (c < 127)) || (c == '\f') || (c == '\r') ||
@ -39,6 +49,7 @@ int sbi_getc(void)
static unsigned long nputs(const char *str, unsigned long len)
{
char ch;
unsigned long i;
if (console_dev) {
@ -51,6 +62,11 @@ static unsigned long nputs(const char *str, unsigned long len)
console_dev->console_putc(str[i]);
}
}
} else {
for (i = 0; i < len; i++) {
ch = str[i];
sbi_fifo_enqueue(&console_early_fifo, &ch, true);
}
}
return len;
}
@ -472,8 +488,19 @@ const struct sbi_console_device *sbi_console_get_device(void)
void sbi_console_set_device(const struct sbi_console_device *dev)
{
char ch;
bool flush_early_fifo = false;
if (!dev)
return;
if (!console_dev)
flush_early_fifo = true;
console_dev = dev;
if (flush_early_fifo) {
while (!sbi_fifo_dequeue(&console_early_fifo, &ch))
sbi_putc(ch);
}
}