<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_REOPENED " title="REOPENED --- - [HSW bisected]igt/module_reload causes [drm:hsw_unclaimed_reg_check] *ERROR* Unclaimed write to 44004 and system hang with headless, with power well disabled" href="https://bugs.freedesktop.org/show_bug.cgi?id=67813#c39">Comment # 39</a> on <a class="bz_bug_link bz_status_REOPENED " title="REOPENED --- - [HSW bisected]igt/module_reload causes [drm:hsw_unclaimed_reg_check] *ERROR* Unclaimed write to 44004 and system hang with headless, with power well disabled" href="https://bugs.freedesktop.org/show_bug.cgi?id=67813">bug 67813</a> from <a class="email" href="mailto:przanoni@gmail.com" title="Paulo Zanoni <przanoni@gmail.com>"> Paulo Zanoni</a> <pre>(In reply to <a href="show_bug.cgi?id=67813#c38">comment #38</a>) > I did some more investigation, and it seems the Kernel gets stuck on an > infinite loop that keeps calling VGA. I added some printks, and I at the > moment we do the "echo 0" to the bind file (accidentally hit the "Save Changes" button) I did some more investigation, and it seems the Kernel gets stuck on an infinite loop that keeps calling VGA functions. I added some printks, and at the moment we do the "echo 0" to the bind file, we keep printing this forever: [ 431.878277] === write_vga [ 431.878278] === vgacon_set_cursor_size [ 431.878297] [drm:intel_uncore_check_errors] *ERROR* Unclaimed register before interrupt [ 431.878331] === vgacon_cursor [ 431.878332] === vgacon_restore_screen [ 431.878332] === write_vga [ 431.878333] === vgacon_set_cursor_size [ 431.878373] === vgacon_dummy [ 431.878373] === vgacon_scroll [ 431.878374] === vgacon_restore_screen [ 431.878374] === vgacon_scrollback_update [ 431.878435] === vga_set_mem_top [ 431.878435] === write_vga [ 431.878439] === vgacon_dummy [ 431.878440] === vgacon_scroll [ 431.878440] === vgacon_restore_screen [ 431.878440] === vgacon_scrollback_update [ 431.878501] === vga_set_mem_top [ 431.878502] === write_vga [ 431.878503] === vgacon_cursor [ 431.878503] === vgacon_restore_screen [ 431.878504] === write_vga [ 431.878505] === vgacon_set_cursor_size [ 431.878524] [drm:intel_uncore_check_errors] *ERROR* Unclaimed register before interrupt [ 431.878559] === vgacon_cursor [ 431.878559] === vgacon_restore_screen [ 431.878559] === write_vga [ 431.878560] === vgacon_set_cursor_size [ 431.878601] === vgacon_dummy [ 431.878601] === vgacon_scroll Also, the function that triggers the unclaimed register is clearly vgacon_set_cursor_size. It looks like we're stuck in an infinite loop inside console_unlock. The code that seems to fix the problem is just: vga_get_uninterruptible(dev->pdev, VGA_RSRC_LEGACY_IO); val = inb(VGA_MSR_READ); outb(val & ~VGA_MSR_MEM_EN, VGA_MSR_WRITE); vga_set_legacy_decoding(dev->pdev, VGA_RSRC_LEGACY_IO | VGA_RSRC_NORMAL_IO |VGA_RSRC_NORMAL_MEM); vga_put(dev->pdev, VGA_RSRC_LEGACY_IO);</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>