glamor: created pixmap is not clean on intel

[cepelinas9000]

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Describe your issue

There where multiple reports and I saw myself window with random artifacts and glitches. I writing here because i think found a reproducer for big part of them.

Didn't deeply investigate, problem is on intel mesa (tried on nvidia with modesetting dirver it was clear - but it can be because lucky) created glamor pixmap gpu memory is not cleared and contains what previously was in that region. For example using my minimal code i get:

Or similar

Steps to reproduce

1. Have intel gpu for desktop rendering
2. Blit just created pixmap:

// compile with: gcc -o main main.c `pkg-config --cflags --libs xcb`

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#include <assert.h>
#include <math.h>


#include <gbm.h>
#include <epoxy/egl.h>


#include <xcb/xproto.h>
#include <xcb/dri3.h>


xcb_window_t create_xcb_window(xcb_connection_t *conn, xcb_screen_t *screen){
    xcb_window_t window = xcb_generate_id(conn);
    uint32_t mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
    uint32_t values[2] = {
        screen->black_pixel,
        XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS
    };

    xcb_create_window(conn,
                      XCB_COPY_FROM_PARENT,   // depth
                      window,                 // window id
                      screen->root,           // parent window
                      0, 0,                   // x, y
                      640, 640,               // width, height
                      1,                      // border width
                      XCB_WINDOW_CLASS_INPUT_OUTPUT,
                      screen->root_visual,
                      mask,
                      values
                      );

    // 4. Map (show) the window
    xcb_map_window(conn, window);
    xcb_flush(conn);

    return window;
}


int main(int argc,char *argv[])
{
    xcb_connection_t *conn = xcb_connect(NULL, NULL);
    xcb_screen_t *screen = xcb_setup_roots_iterator(xcb_get_setup(conn)).data;
    xcb_window_t window = create_xcb_window(conn,screen);
    xcb_gcontext_t gc;

    gc = xcb_generate_id(conn);
    xcb_create_gc(conn, gc, window, 0, NULL);

    int img_width = 400;
    int img_height = 400;

    // 6. Create a pixmap to hold the image
    //    The pixmap must have the same depth as the window
    xcb_pixmap_t pixmap = xcb_generate_id(conn);
    xcb_create_pixmap(conn,
                      screen->root_depth,     // depth
                      pixmap,                 // pixmap id
                      window,                 // drawable (used for depth/visual)
                      img_width,
                      img_height
                      );

    while (1) {
        xcb_generic_event_t *event = xcb_wait_for_event(conn);
        if (!event) break;

        switch (event->response_type & ~0x80) {
        case XCB_EXPOSE: {
            // Draw the pixmap onto the window using xcb_copy_area
            xcb_copy_area(conn,
                          pixmap,     // source drawable
                          window,     // destination drawable
                          gc,         // graphics context
                          0, 0,       // source x, y
                          0, 0,     // destination x, y
                          img_width,
                          img_height
                          );
            xcb_flush(conn);
            break;
        }

        case XCB_KEY_PRESS:
            // Exit on any key press
            free(event);
            goto out;
        }
        free(event);
    }

    out:
    return 0;
}

3. compile it and enjoy random artifacts

What did you expect?

Have clear window without artifacts.

Additional Information

No response

Extra fields

• I have checked the existing issues
• I have read the Contributing Guidelines
• I'd like to work on this issue