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vclog: Report when gpu_mem is too low for logs #215

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Merged
popcornmix merged 1 commit into from
Oct 2, 2026
Merged

vclog: Report when gpu_mem is too low for logs #215

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47 changes: 44 additions & 3 deletions vclog/vclog.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <fcntl.h>
#include <getopt.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
Expand Down Expand Up @@ -75,6 +76,9 @@ enum
#define ARRAY_SIZE(_a) (sizeof(_a)/sizeof(_a[0]))

#define FBIODMACOPY _IOW('z', 0x22, struct fb_dmacopy)
#define IOCTL_MBOX_PROPERTY _IOWR(100, 0, char *)
#define MBOX_TAG_GET_VC_MEMORY 0x00010006
#define MIN_GPU_MEM_FOR_LOGS (16 * 1024 * 1024)

#ifdef DEBUG
#define DLOG(...) printf(__VA_ARGS__)
Expand Down Expand Up @@ -104,12 +108,13 @@ static int dma_fd = -1;
static char *vc_map = MAP_FAILED;

static bool find_logs(uint32_t *logs_start, uint32_t *logs_size);
static bool get_gpu_mem_size(uint32_t *size);
static bool prepare_vc_mapping(uint32_t vc_start, uint32_t vc_size);
static void destroy_vc_mapping(void);
static void read_vc_mem(uint32_t vc_addr, uint32_t size, void *dest);
static uint32_t log_copy_wrap(const char *log_buffer, uint32_t log_size,
uint32_t offset, uint32_t len, char *dest);
static void die(const char *msg);
static void die(const char *fmt, ...) __attribute__((format(printf, 1, 2), noreturn));

int32_t main(int32_t argc, char *argv[])
{
Expand Down Expand Up @@ -143,7 +148,14 @@ int32_t main(int32_t argc, char *argv[])

// find the address and size of the logs in VC memory
if (!find_logs(&logs_start_vc, &logs_size))
{
uint32_t gpu_mem;

if (get_gpu_mem_size(&gpu_mem) && gpu_mem <= MIN_GPU_MEM_FOR_LOGS)
die("Logs are not available with gpu_mem=%u. "
"Increase gpu_mem in config.txt", gpu_mem >> 20);
die("Could not determine logs location from Device Tree");
}

if (!prepare_vc_mapping(logs_start_vc, logs_size))
die("Cannot access logs");
Expand Down Expand Up @@ -355,6 +367,29 @@ static bool find_logs(uint32_t *logs_start, uint32_t *logs_size)
return ret;
}

static bool get_gpu_mem_size(uint32_t *size)
{
uint32_t buf[8] = {
sizeof(buf), 0,
MBOX_TAG_GET_VC_MEMORY, 8, 0, 0, 0,
0
};
int fd;
int err;

fd = open("/dev/vcio", 0);
if (fd < 0)
return false;

err = ioctl(fd, IOCTL_MBOX_PROPERTY, buf);
close(fd);
if (err < 0 || buf[1] != 0x80000000)
return false;

*size = buf[6];
return true;
}

static bool prepare_vc_mapping(uint32_t vc_start, uint32_t vc_size)
{
const char *dma_filenames[] = { "/dev/vc-mem", "/dev/fb0" };
Expand Down Expand Up @@ -498,8 +533,14 @@ static uint32_t log_copy_wrap(const char *log_buffer, uint32_t log_size,
}
}

static void die(const char *msg)
static void die(const char *fmt, ...)
{
fprintf(stderr, "Fatal error: %s\n", msg);
va_list ap;

va_start(ap, fmt);
fprintf(stderr, "Fatal error: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
va_end(ap);
exit(EXIT_FAILURE);
}
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