Re: [Xen-devel] [Qemu-devel] Cirrus VGA slow screen update, show blank screen last 13s or so for windows XP guest

["Gonglei (Arei)" <arei.gonglei@xxxxxxxxxx>]

Hi,
The fundamental reason is traditional qemu-dm and upstream qemu using a 
different vgabios-cirrus.bin,
qemu-dm is using xen-4.1.2/tools/firmware/vgabios/ 
VGABIOS-lgpl-latest.cirrus.bin, 
but upstream qemu is using qemu-1.2.2/pc-bios/vgabios-cirrus.bin

the pivotal patch is :

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1193391667 -3600
# Node ID d31f63db5f1e88deadc5461adda07b77c22873d7
# Parent  413107fa49a50e5c61ac390dc1870d8995b2a012

x86, hvm: Allow Cirrus VGA BIOS to clear framebuffer with minimal PIO writes.

Signed-off-by: Ben Guthro <bguthro@xxxxxxxxxxxxxx>
Signed-off-by: Gary Grebus <ggrebus@xxxxxxxxxxxxxxx>

diff -r 413107fa49a5 -r d31f63db5f1e tools/firmware/vgabios/clext.c
--- a/tools/firmware/vgabios/clext.c    Fri Oct 26 10:33:12 2007 +0100
+++ b/tools/firmware/vgabios/clext.c    Fri Oct 26 10:41:07 2007 +0100
@@ -1489,14 +1489,26 @@
   mov dx, #0x3ce
   out dx, ax
   push ax
-  mov cx, #0xa000
-  mov es, cx
-  xor di, di
+
+;; Windows Vista appears to be emulating this sequence as part of changing 
+;; screen resolution, but it generates 4096 writes per iteration.
+;; Instead, use a magic register sequence to write the whole bank.
+;;mov cx, #0xa000
+;;mov es, cx
+;;xor di, di
+;;mov ax, si
+;;mov cx, #8192
+;;cld
+;;rep
+;;    stosw
   mov ax, si
-  mov cx, #8192
-  cld
-  rep
-      stosw
+  shl ax, #8
+  mov al, #0xfe
+  out dx, ax   ;; Low byte of value to be written to the bank
+  mov ax, si
+  mov al, #0xff  
+  out dx, ax    ;; High byte and trigger the write
+
   pop ax
   inc ah
   cmp ah, bl
diff -r 413107fa49a5 -r d31f63db5f1e tools/ioemu/hw/cirrus_vga.c
--- a/tools/ioemu/hw/cirrus_vga.c       Fri Oct 26 10:33:12 2007 +0100
+++ b/tools/ioemu/hw/cirrus_vga.c       Fri Oct 26 10:41:07 2007 +0100
@@ -294,6 +294,7 @@
 
 static void cirrus_bitblt_reset(CirrusVGAState *s);
 static void cirrus_update_memory_access(CirrusVGAState *s);
+static void cirrus_vga_mem_writew(void *opaque, target_phys_addr_t addr, 
uint32_t val);
 
 /***************************************
  *
@@ -1497,6 +1498,17 @@
     case 0x31:                 // BLT STATUS/START
        cirrus_write_bitblt(s, reg_value);
        break;
+
+       // Extension to allow BIOS to clear 16K VRAM bank in one operation
+    case 0xFE:
+       s->gr[reg_index] = reg_value;  // Lower byte of value to be written
+       break;
+    case 0xFF: {
+       target_phys_addr_t addr;
+       for (addr = 0xa0000; addr < 0xa4000; addr += 2)
+           cirrus_vga_mem_writew(s, addr, (reg_value << 8) | s->gr[0xFE]);
+       }
+       break;
     default:
 #ifdef DEBUG_CIRRUS
        printf("cirrus: outport gr_index %02x, gr_value %02x\n", reg_index,

By replacing the vgabios-cirrus.bin, the windows XP guest screen updating is 
fast with upstream qemu.

And I test the latest vgabios-0.7a come from 
http://www.nongnu.org/vgabios/#DOWNLOAD
but the problem of blank screen remain.

Best Regards!
-Gonglei
 

> -----Original Message-----
> From: Gonglei (Arei)
> Sent: Friday, August 16, 2013 5:10 PM
> To: Gonglei (Arei); 'Pasi KÃrkkÃinen'
> Cc: 'Gerd Hoffmann'; 'Andreas FÃrber'; Hanweidong; Luonengjun;
> 'qemu-devel@xxxxxxxxxx'; 'xen-devel@xxxxxxxxxxxxx'; 'Anthony Liguori';
> Huangweidong (Hardware); 'Ian.Jackson@xxxxxxxxxxxxx'; 'Anthony Liguori';
> Yanqiangjun; Yangxiaowei
> Subject: RE: [Xen-devel] [Qemu-devel] Cirrus VGA slow screen update, show
> blank screen last 13s or so for windows XP guest
> 
> Hi, all
> I compared the traditional qemu-dm and upstream qemu,
> and I found the upstream qemu will create the expansion ROM at f3000000,
> but qemu-dm don't.
> the details as below (by "lspci -vnnn"):
> 
> 1) traditional qemu-dm:
> 00:02.0 VGA compatible controller [0300]: Cirrus Logic GD 5446 [1013:00b8]
> (prog-if 00 [VGA controller])
>       Subsystem: XenSource, Inc. Device [5853:0001]
>       Flags: bus master, fast devsel, latency 0, IRQ 11
>       Memory at f0000000 (32-bit, prefetchable) [size=32M]
>       Memory at f3000000 (32-bit, non-prefetchable) [size=4K]
>       Kernel modules: cirrusfb
> 
> 2) upstream qemu:
> 00:02.0 VGA compatible controller [0300]: Cirrus Logic GD 5446 [1013:00b8]
> (prog-if 00 [VGA controller])
>       Subsystem: XenSource, Inc. Device [5853:0001]
>       Physical Slot: 2
>       Flags: bus master, fast devsel, latency 0, IRQ 11
>       Memory at f0000000 (32-bit, prefetchable) [size=32M]
>       Memory at f3020000 (32-bit, non-prefetchable) [size=4K]
>       Expansion ROM at f3000000 [disabled] [size=64K]
>       Kernel modules: cirrusfb
> 
> I tried to simply delete the expansion ROM at function pci_add_option_rom,
> such as
> 
>   //pci_register_bar(pdev, PCI_ROM_SLOT, 0, &pdev->rom);
> 
> but the VNC viewer only can see black screen, but RDP works well.
> Any ideas about the cirrus's expansion ROM?
> Slow screen refresh has any relationship with cirrus's expansion ROM?
> Thank you in advanceï
> 
> BTW, I added some log in stdvga.c(xen-4.1.2/xen/arch/x86/hvm):
> static int stdvga_intercept_mmio(ioreq_t *p)
> {
>     struct domain *d = current->domain;
>     struct hvm_hw_stdvga *s = &d->arch.hvm_domain.stdvga;
>     int buf = 0, rc;
>     static int count_1 = 0;
>     static int count_2 = 0;
> 
>     if ( p->size > 8 )
>     {
>         gdprintk(XENLOG_WARNING, "invalid mmio size %d\n", (int)p->size);
>         return X86EMUL_UNHANDLEABLE;
>     }
> 
>     spin_lock(&s->lock);
> 
>     if ( s->stdvga && s->cache )
>     {
>         switch ( p->type )
>         {
>         case IOREQ_TYPE_COPY:
>             buf = mmio_move(s, p);
>             count_1++;
>             if (count_1 % 1000 == 0)
>                 gdprintk(XENLOG_WARNING, " =uvp= enter mmio_move,
> count_1=%d\n", count_1);
>             if ( !buf )
>                 s->cache = 0;
>             break;
>         default:
>             gdprintk(XENLOG_WARNING, "unsupported mmio request
> type:%d "
>                      "addr:0x%04x data:0x%04x size:%d count:%d
> state:%d "
>                      "isptr:%d dir:%d df:%d\n",
>                      p->type, (int)p->addr, (int)p->data, (int)p->size,
>                      (int)p->count, p->state,
>                      p->data_is_ptr, p->dir, p->df);
>             s->cache = 0;
>         }
>     }
>     else
>     {
>         buf = (p->dir == IOREQ_WRITE);
>         count_2++;
>         if (count_2 % 5000 == 0)
>             gdprintk(XENLOG_WARNING, " >>> vga mmio count_2=%d\n",
> count_2);
>     }
> 
>     rc = (buf && hvm_buffered_io_send(p));
> 
>     spin_unlock(&s->lock);
> 
>     return rc ? X86EMUL_OKAY : X86EMUL_UNHANDLEABLE;
> }
> 
> and I got the below result with upstream qemu and tranditional qemu-dm:
> 
>  1) traditional qemu-dm:
> (XEN) stdvga.c:152:d2 entering stdvga and caching modes
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=460000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=461000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=462000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=463000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=464000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=465000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=466000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=467000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=468000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=469000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=470000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=471000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=472000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=473000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=474000
> (XEN) stdvga.c:577:d2  =uvp= enter mmio_move, count_1=475000
> (XEN) stdvga.c:156:d2 leaving stdvga
> 
>  2) upstream qemu:
> (XEN) stdvga.c:152:d1 entering stdvga and caching modes
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=233000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=234000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=235000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=236000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=237000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=238000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=239000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=240000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=241000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=242000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=243000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=244000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=245000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=246000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=247000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=248000
> (XEN) stdvga.c:577:d1  =uvp= enter mmio_move, count_1=249000
> (XEN) stdvga.c:156:d1 leaving stdvga
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=8400000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=8405000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=8410000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=8415000
>   ... ... //Omit some similar
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=12570000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=12575000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=12580000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=12585000
> (XEN) stdvga.c:596:d1  >>> vga mmio count_2=12590000
> 
> Upstream qemu has lot's of MMIO access Memory region 0xa0000~0xc0000
> than traditional qemu-dm.
> 
> Best Regards!
> 
> -Gonglei
> 
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