[Bug]: dri3: xcb_dri3_buffers_from_pixmap not working #841
Description
Background
I have two devices, one is Redmi Note 11T Pro+ (mtk device) (currently using it because of LCD), the other Redmi K60 (qcom device) (already sold out).
For years I always dream of running a full accelerated KDE Plasma in a container in termux-x11.
On Redmi K60, turnip works well on termux x11 with dri3 and performance is good. Zink also works. Then I want to run kwin_x11, but it only renders window frame including title bar and shadow. The window content is full transparent.
On Redmi Note 11T Pro+ sadly there is no such native high performance open source vulkan driver like turnip. So I used sysvk with vulkan-wsi-layer (from @xMeM) on libhybris in gnu/linux container. Vulkan now also works well with dri3 on termux-x11. Zink also works. The performance is also good. (See more in https://github.com/kde-yyds/android-vulkan-bridge)
Then I tried to run kwin_x11 but it has the same effect on turnip zink (and freedreno).
The key problem is likely to be the bad pixmap error. MESA: error: kopper: could not create texture from pixmap (4).
About the dri3 issue
Then I searched for the error message and found:
mesa-24.2.7/src/gallium/frontends/dri/kopper.c:
#ifdef HAVE_DRI3_MODIFIERS
if (drawable->has_modifiers) {
xcb_dri3_buffers_from_pixmap_cookie_t bps_cookie;
xcb_dri3_buffers_from_pixmap_reply_t *bps_reply;
xcb_generic_error_t *error;
bps_cookie = xcb_dri3_buffers_from_pixmap(conn, pixmap);
bps_reply = xcb_dri3_buffers_from_pixmap_reply(conn, bps_cookie, &error);
if (!bps_reply) {
mesa_loge("kopper: could not create texture from pixmap (%u)", error->error_code);
return NULL;
}
drawable->image =
dri3_create_image_from_buffers(conn, bps_reply, fourcc,
screen, &driVkImageExtension,
drawable);
if (!drawable->image)
return NULL;
width = bps_reply->width;
height = bps_reply->height;
free(bps_reply);
} else
#endif
It returns NULL here to avoid crash. So by commenting the early return here I got a bt.
Thread 1 "kwin_x11" received signal SIGSEGV, Segmentation fault.
kopper_get_pixmap_buffer () at ../mesa-24.2.7/src/gallium/frontends/dri/kopper.c:360
360 dri3_create_image_from_buffers(conn, bps_reply, fourcc,
(gdb) bt
#0 kopper_get_pixmap_buffer () at ../mesa-24.2.7/src/gallium/frontends/dri/kopper.c:360
#1 kopper_allocate_textures () at ../mesa-24.2.7/src/gallium/frontends/dri/kopper.c:557
#2 0x0000007feef48174 in dri_st_framebuffer_validate () at ../mesa-24.2.7/src/gallium/frontends/dri/dri_drawable.c:79
#3 0x0000007feef47e94 in dri_drawable_validate_att () at ../mesa-24.2.7/src/gallium/frontends/dri/dri_drawable.c:249
#4 dri_set_tex_buffer2 () at ../mesa-24.2.7/src/gallium/frontends/dri/dri_drawable.c:266
#5 0x00000055555ca4a8 in ?? ()
#6 0x00000055555ca5d8 in ?? ()
#7 0x0000007ff7655ed4 in KWin::SurfaceItem::preprocess() () from /usr/lib/libkwin.so.6
#8 0x0000007ff764bd9c in KWin::ItemRendererOpenGL::createRenderNode(KWin::Item*, KWin::ItemRendererOpenGL::RenderContext*)
() from /usr/lib/libkwin.so.6
#9 0x0000007ff764c3c8 in KWin::ItemRendererOpenGL::createRenderNode(KWin::Item*, KWin::ItemRendererOpenGL::RenderContext*)
() from /usr/lib/libkwin.so.6
#10 0x0000007ff764ce80 in KWin::ItemRendererOpenGL::renderItem(KWin::RenderTarget const&, KWin::RenderViewport const&, KWin::Item*, int, QRegion const&, KWin::WindowPaintData const&) () from /usr/lib/libkwin.so.6
#11 0x0000007ff76602e8 in KWin::WorkspaceScene::paintWindow(KWin::RenderTarget const&, KWin::RenderViewport const&, KWin::WindowItem*, int, QRegion const&) () from /usr/lib/libkwin.so.6
#12 0x0000007ff7660660 in KWin::WorkspaceScene::paintSimpleScreen(KWin::RenderTarget const&, KWin::RenderViewport const&, int, QRegion const&) () from /usr/lib/libkwin.so.6
#13 0x0000007ff76600b0 in KWin::WorkspaceScene::paint(KWin::RenderTarget const&, QRegion const&) ()
from /usr/lib/libkwin.so.6
#14 0x0000007ff76524c0 in KWin::SceneDelegate::paint(KWin::RenderTarget const&, QRegion const&) () from /usr/lib/libkwin.so.6
#15 0x0000007ff7493860 in KWin::Compositor::paintPass(KWin::RenderLayer*, KWin::RenderTarget const&, QRegion const&) ()
from /usr/lib/libkwin.so.6
#16 0x0000007ff77727dc in KWin::X11Compositor::composite(KWin::RenderLoop*) () from /usr/lib/libkwin.so.6
#17 0x0000007ff42faaa0 in ?? () from /usr/lib/libQt6Core.so.6
#18 0x0000007ff74bfd38 in KWin::RenderLoop::frameRequested(KWin::RenderLoop*) () from /usr/lib/libkwin.so.6
#19 0x0000007ff74c0eac in KWin::RenderLoopPrivate::dispatch() () from /usr/lib/libkwin.so.6
#20 0x0000007ff42faaa0 in ?? () from /usr/lib/libQt6Core.so.6
#21 0x0000007ff430e82c in QTimer::timeout(QTimer::QPrivateSignal) () from /usr/lib/libQt6Core.so.6
#22 0x0000007ff42eb0b8 in QObject::event(QEvent*) () from /usr/lib/libQt6Core.so.6
#23 0x0000007ff544f6d4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQt6Widgets.so.6
#24 0x0000007ff4281b4c in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/libQt6Core.so.6
#25 0x0000007ff4470fcc in QTimerInfoList::activateTimers() () from /usr/lib/libQt6Core.so.6
#26 0x0000007ff45c9710 in ?? () from /usr/lib/libQt6Core.so.6
#27 0x0000007ff255af9c in ?? () from /usr/lib/libglib-2.0.so.0
The issue is that xcb_dri3_buffers_from_pixmap_reply is returning NULL with error code 4 (BadPixmap), indicating that the X11 server doesn't recognize the pixmap ID as valid.
Then I used claude to generate a small program to test this function.
// compile with gcc -o dri3_pixmap_test dri3_pixmap_test.c -lxcb -lxcb-dri3
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <xcb/xcb.h>
#include <xcb/dri3.h>
#include <xcb/xcb_aux.h>
#include <xcb/xproto.h>
int main(void) {
xcb_connection_t *conn;
xcb_screen_t *screen;
xcb_pixmap_t pixmap;
xcb_drawable_t drawable;
xcb_gcontext_t gc;
int screen_num;
xcb_generic_error_t *error;
/* Connect to the X server */
conn = xcb_connect(NULL, &screen_num);
if (xcb_connection_has_error(conn)) {
fprintf(stderr, "Error connecting to X server\n");
return 1;
}
/* Get the screen */
screen = xcb_setup_roots_iterator(xcb_get_setup(conn)).data;
/* Check if DRI3 is available */
const xcb_query_extension_reply_t *dri3_ext;
dri3_ext = xcb_get_extension_data(conn, &xcb_dri3_id);
if (!dri3_ext || !dri3_ext->present) {
fprintf(stderr, "DRI3 extension not available\n");
xcb_disconnect(conn);
return 1;
}
/* Create a pixmap */
pixmap = xcb_generate_id(conn);
xcb_create_pixmap(conn, screen->root_depth, pixmap, screen->root, 256, 256);
/* Create a GC */
gc = xcb_generate_id(conn);
xcb_create_gc(conn, gc, pixmap, 0, NULL);
/* Draw something on the pixmap */
uint32_t values[1] = { screen->white_pixel };
xcb_change_gc(conn, gc, XCB_GC_FOREGROUND, values);
xcb_rectangle_t rect = { 0, 0, 256, 256 };
xcb_poly_fill_rectangle(conn, pixmap, gc, 1, &rect);
/* Try to get buffers from pixmap */
xcb_dri3_buffers_from_pixmap_cookie_t bfp_cookie;
xcb_dri3_buffers_from_pixmap_reply_t *bfp_reply;
bfp_cookie = xcb_dri3_buffers_from_pixmap(conn, pixmap);
bfp_reply = xcb_dri3_buffers_from_pixmap_reply(conn, bfp_cookie, &error);
if (!bfp_reply) {
if (error) {
fprintf(stderr, "Error: xcb_dri3_buffers_from_pixmap failed with error code %d\n",
error->error_code);
free(error);
} else {
fprintf(stderr, "Error: xcb_dri3_buffers_from_pixmap failed without error\n");
}
} else {
printf("Success! xcb_dri3_buffers_from_pixmap returned data:\n");
printf("Width: %d, Height: %d\n", bfp_reply->width, bfp_reply->height);
printf("Modifier type: %lu\n", (unsigned long)bfp_reply->modifier);
free(bfp_reply);
}
/* Clean up */
xcb_free_gc(conn, gc);
xcb_free_pixmap(conn, pixmap);
xcb_disconnect(conn);
return 0;
}
It works on my PC but right returns error in the container on my phone with termux-x11 X server.
Maybe by solving this we can run kwin_x11 normally?
Is it an error in termux-x11's dri3 implementation? Can you help me debug and maybe fix it? Thanks a lot!