Re: scratch/igc fe90d556834: Make glyphs ambiguous roots

[Helmut Eller]

On Sun, Jul 28 2024, Gerd Moellmann wrote:

>     We cannot trace glyphs in fix_window because we don't have exclusive
>     access to glyph_rows and glyphs. (An optimal solution would allocate
>     glyphs from MPS, and change data structures in a way that everything
>     needed (row->used, row->enabled_p) is available for the scanner.)

I don't understand this.  Glyph_rows aren't allocated in MPS-managed
memory so there are no memory barriers to worry about.  While fix_frame
runs, all other threads are suspended.  So why don't we have exclusive
access?  And why is it not a problem for FRAME_FONT, FRAME_DISPLAY_INFO,
etc?