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Message-ID: <7ff51c5b-939e-47d9-8c3b-3c596565d114@redhat.com>
Date: Mon, 1 Sep 2025 15:04:26 +0200
From: Jocelyn Falempe <jfalempe@...hat.com>
To: Thomas Zimmermann <tzimmermann@...e.de>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
Simona Vetter <simona@...ll.ch>,
Javier Martinez Canillas <javierm@...hat.com>, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 3/3] drm/panic: Add a kconfig option to dump kunits
results to png
On 27/08/2025 12:45, Thomas Zimmermann wrote:
> Hi
>
> Am 21.08.25 um 11:49 schrieb Jocelyn Falempe:
>> 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.
>
> May I suggest to export the raw image via debugfs? Debugfs can also
> export additional information in additional files, such as width/height/
> stride/format. This could provide the real/last image on the fly, simply
> by reading the files. No workarounds or encodings needed.
I'm looking into that. The difficulty is to get the debugfs content
outside of the test kernel. As I'm using a uml kernel for testing, I
will need a special initrd, and a way to share files with the host.
Best regards,
--
Jocelyn
>
> Best regards
> Thomas
>
>>
>> Signed-off-by: Jocelyn Falempe <jfalempe@...hat.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");
>> + vfree(compressed);
>> + vfree(dst);
>> +
>> +}
>> +
>> +// Ignore pixel format, use 1bit per pixel in monochrome.
>> static void drm_test_panic_set_pixel(struct drm_scanout_buffer *sb,
>> unsigned int x,
>> unsigned int y,
>> u32 color)
>> {
>> + int stride = DIV_ROUND_UP(sb->width, 8);
>> + size_t off = x / 8 + y * stride;
>> + u8 shift = 7 - (x % 8);
>> + u8 *fb = (u8 *) sb->private;
>> +
>> + if (color)
>> + fb[off] |= 1 << shift;
>> + else
>> + fb[off] &= ~(1 << shift);
>> }
>> +#else
>> +static void dump_image(u8 *fb, unsigned int width, unsigned int
>> height) {}
>> +static void drm_test_panic_set_pixel(struct drm_scanout_buffer *sb,
>> + unsigned int x,
>> + unsigned int y,
>> + u32 color)
>> +{
>> +}
>> +#endif
>> +
>> static void drm_test_panic_screen_user_set_pixel(struct kunit *test)
>> {
>> struct drm_scanout_buffer *sb = test->priv;
>> const struct drm_test_mode *params = test->param_value;
>> + int fb_size;
>> + u8 *fb;
>> sb->format = drm_format_info(params->format);
>> + fb_size = DIV_ROUND_UP(params->width, 8) * params->height;
>> +
>> + fb = vzalloc(fb_size);
>> + KUNIT_ASSERT_NOT_NULL(test, fb);
>> + sb->private = fb;
>> sb->set_pixel = drm_test_panic_set_pixel;
>> sb->width = params->width;
>> sb->height = params->height;
>> params->draw_screen(sb);
>> + if (params->format == DRM_FORMAT_XRGB8888)
>> + dump_image(fb, sb->width, sb->height);
>> +
>> + vfree(fb);
>> }
>> static void drm_test_panic_desc(const struct drm_test_mode *t, char
>> *desc)
>> diff --git a/scripts/kunitpanic2png.py b/scripts/kunitpanic2png.py
>> new file mode 100755
>> index 000000000000..e292afd7422c
>> --- /dev/null
>> +++ b/scripts/kunitpanic2png.py
>> @@ -0,0 +1,53 @@
>> +#!/usr/bin/env python3
>> +# SPDX-License-Identifier: MIT
>> +#
>> +# Copyright (c) 2025 Red Hat.
>> +# Author: Jocelyn Falempe <jfalempe@...hat.com>
>> +
>> +from argparse import ArgumentParser
>> +from PIL import Image
>> +import base64
>> +import zlib
>> +
>> +def get_dim(s):
>> + (w, h) = s.split('x')
>> + return (int(w), int(h))
>> +
>> +def draw_image(img_data, width, height, n_img):
>> +
>> + decoded = base64.b64decode(img_data)
>> + unzipped = zlib.decompress(decoded)
>> +
>> + img = Image.frombytes("1", (width, height), unzipped)
>> + fname = f"panic_screen_{n_img}.png"
>> + img.save(fname)
>> + print(f"Image {width}x{height} saved to {fname}")
>> +
>> +def main():
>> + parser = ArgumentParser(
>> + prog="kunitpanic2png",
>> + description="Read drm_panic kunit logs and translate that to
>> png files")
>> +
>> + parser.add_argument("filename", help="log file from kunit,
>> usually test.log")
>> +
>> + parsing_img = False
>> + img_data = ""
>> + n_img = 0
>> +
>> + args = parser.parse_args()
>> + with open(args.filename, "r") as f:
>> + for line in f.readlines():
>> + if line.startswith("KUNIT PANIC IMAGE DUMP START"):
>> + parsing_img = True
>> + width, height = get_dim(line.split()[-1])
>> + continue
>> + if line.startswith("KUNIT PANIC IMAGE DUMP END"):
>> + draw_image(img_data, width, height, n_img)
>> + parsing_img = False
>> + img_data = ""
>> + n_img += 1
>> + continue
>> + if parsing_img:
>> + img_data += line.strip()
>> +
>> +main()
>
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