Hi,
On Thu, Aug 21, 2025 at 11:49:07AM +0200, Jocelyn Falempe wrote:
> This is a bit hacky, but very handy if you want to customize the
> panic screen.
> It allows to dump the generated images to the logs, and then a python
> script can convert it to .png files. It makes it easy to check how
> the panic screen will look on different resolutions, without having
> to crash a VM.
> To not pollute the logs, it uses a monochrome framebuffer, compress
> it with zlib, and base64 encode it.
>
> Signed-off-by: Jocelyn Falempe <jfale...@redhat.com>
> ---
> drivers/gpu/drm/Kconfig.debug | 14 ++++
> drivers/gpu/drm/tests/drm_panic_test.c | 111 +++++++++++++++++++++++++
> scripts/kunitpanic2png.py | 53 ++++++++++++
> 3 files changed, 178 insertions(+)
> create mode 100755 scripts/kunitpanic2png.py
>
> diff --git a/drivers/gpu/drm/Kconfig.debug b/drivers/gpu/drm/Kconfig.debug
> index 05dc43c0b8c5..d8ae85132d32 100644
> --- a/drivers/gpu/drm/Kconfig.debug
> +++ b/drivers/gpu/drm/Kconfig.debug
> @@ -84,6 +84,20 @@ config DRM_KUNIT_TEST
>
> If in doubt, say "N".
>
> +config DRM_PANIC_KUNIT_TEST_DUMP
> + bool "Enable screen dump to logs in KUnit tests for drm_panic"
> + default n
> + depends on DRM && DRM_PANIC && DRM_KUNIT_TEST
> + select ZLIB_DEFLATE
> + help
> + This allows to dump the panic screen to the KUnit tests logs.
> + It's possible with a small python script to write pngs from the logs.
> +
> + This is only to help developers customizing the drm_panic screen,
> + checking the result for different resolutions.
> +
> + If in doubt, say "N"
> +
> config DRM_TTM_KUNIT_TEST
> tristate "KUnit tests for TTM" if !KUNIT_ALL_TESTS
> default n
> diff --git a/drivers/gpu/drm/tests/drm_panic_test.c
> b/drivers/gpu/drm/tests/drm_panic_test.c
> index 46ff3e5e0e5d..8cddb845aea9 100644
> --- a/drivers/gpu/drm/tests/drm_panic_test.c
> +++ b/drivers/gpu/drm/tests/drm_panic_test.c
> @@ -115,24 +115,135 @@ static void drm_test_panic_screen_user_page(struct
> kunit *test)
> kfree(pages);
> }
>
> +#ifdef CONFIG_DRM_PANIC_KUNIT_TEST_DUMP
> +#include <linux/base64.h>
> +#include <linux/delay.h>
> +#include <linux/zlib.h>
> +
> +#define LINE_LEN 128
> +
> +#define COMPR_LEVEL 6
> +#define WINDOW_BITS 12
> +#define MEM_LEVEL 4
> +
> +static int compress_image(u8 *src, int size, u8 *dst)
> +{
> + struct z_stream_s stream;
> +
> + stream.workspace = kmalloc(zlib_deflate_workspacesize(WINDOW_BITS,
> MEM_LEVEL),
> + GFP_KERNEL);
> +
> + if (zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
> + MEM_LEVEL, Z_DEFAULT_STRATEGY) != Z_OK)
> + return -EINVAL;
> +
> + stream.next_in = src;
> + stream.avail_in = size;
> + stream.total_in = 0;
> + stream.next_out = dst;
> + stream.avail_out = size;
> + stream.total_out = 0;
> +
> + if (zlib_deflate(&stream, Z_FINISH) != Z_STREAM_END)
> + return -EINVAL;
> +
> + if (zlib_deflateEnd(&stream) != Z_OK)
> + return -EINVAL;
> +
> + kfree(stream.workspace);
> +
> + return stream.total_out;
> +}
> +
> +static void dump_image(u8 *fb, unsigned int width, unsigned int height)
> +{
> + int len = 0;
> + char *dst;
> + char *compressed;
> + int sent = 0;
> + int stride = DIV_ROUND_UP(width, 8);
> + int size = stride * height;
> +
> + compressed = vzalloc(size);
> + if (!compressed)
> + return;
> + len = compress_image(fb, size, compressed);
> + if (len < 0) {
> + pr_err("Compression failed %d", len);
> + return;
> + }
> +
> + dst = vzalloc(4 * DIV_ROUND_UP(len, 3) + 1);
> + if (!dst)
> + return;
> +
> + len = base64_encode(compressed, len, dst);
> +
> + pr_info("KUNIT PANIC IMAGE DUMP START %dx%d", width, height);
> + while (len > 0) {
> + char save = dst[sent + LINE_LEN];
> +
> + dst[sent + LINE_LEN] = 0;
> + pr_info("%s", dst + sent);
> + dst[sent + LINE_LEN] = save;
> + sent += LINE_LEN;
> + len -= LINE_LEN;
> + }
> + pr_info("KUNIT PANIC IMAGE DUMP END");The kunit test output format is defined, and we should probably use a diagnostic line for this: https://docs.kernel.org/dev-tools/ktap.html#diagnostic-lines We should probably cc the kunit maintainers about this too. Maxime
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