[PATCH][v3] read actual memory size in qemu-i386

[Patrick Georgi]

Hi,

the attached patch makes the i440bx emulation read the cmos registers of 
the bochs/qemu emulation that carry RAM size information instead of 
assuming 128MB.

Regards,
Patrick

Signed-Off-By: Patrick Georgi

Index: northbridge/intel/i440bxemulation/domain
===================================================================
--- northbridge/intel/i440bxemulation/domain	(revision 689)
+++ northbridge/intel/i440bxemulation/domain	(working copy)
@@ -19,6 +19,5 @@
  */

{
-	ramsize = "128";
    device_operations = "i440bx_domain";
 };
Index: northbridge/intel/i440bxemulation/i440bx.c
===================================================================
--- northbridge/intel/i440bxemulation/i440bx.c	(revision 689)
+++ northbridge/intel/i440bxemulation/i440bx.c	(working copy)
@@ -37,25 +37,40 @@
  * such modified SOFTWARE should be clearly marked, so as not to confuse
  * it with the version available from LANL.
  */
+ /* dynamic qemu ram size detection
+    Copyright 2008 Patrick Georgi 
+    Licensed under the terms of the GNU General Public License v2 or later
+ */

#include <types.h>
 #include <console.h>
 #include <device/device.h>
 #include <device/pci.h>
 #include <string.h>
+#include <io.h>
 #include "i440bx.h"
 #include "statictree.h"

/* Here are the ops for 440BX as a PCI domain. */

+static int inb_cmos(int port)
+{
+	outb(port, 0x70);
+	return inb(0x71);
+}
+
 static void pci_domain_set_resources(struct device *dev)
 {
    struct device *mc_dev;
    u32 tolmk;		/* Top of low mem, Kbytes. */
    int idx;
-	struct northbridge_intel_i440bxemulation_domain_config *device_configuration =
-	    dev->device_configuration;
-	tolmk = device_configuration->ramsize * 1024;
+	/* read large mem memory descriptor
+	   for <16 MB read the more detailed small mem descriptor
+	   all values in kbytes */
+	tolmk = ((inb_cmos(0x35)<<8) |inb_cmos(0x34)) * 64;
+	if (tolmk <= 16 * 1024) {
+		tolmk = (inb_cmos(0x31)<<8) |inb_cmos(0x30);
+	}
    mc_dev = dev->link[0].children;
    if (mc_dev) {
    	idx = 10;

[Peter Stuge]

On Fri, Jun 06, 2008 at 11:01:06PM +0200, Patrick Georgi wrote:
> Index: northbridge/intel/i440bxemulation/domain
>
> --- northbridge/intel/i440bxemulation/domain	(revision 689)
> +++ northbridge/intel/i440bxemulation/domain	(working copy)
> @@ -19,6 +19,5 @@
>   */
>
> {
> ramsize = "128";

Is this parameter now used anywhere else?
> device_operations = "i440bx_domain";
>  };
> Index: northbridge/intel/i440bxemulation/i440bx.c
> ===================================================================
> --- northbridge/intel/i440bxemulation/i440bx.c	(revision 689)
> +++ northbridge/intel/i440bxemulation/i440bx.c	(working copy)
> @@ -37,25 +37,40 @@
> such modified SOFTWARE should be clearly marked, so as not to confuse
> it with the version available from LANL.
>
> */
> /* dynamic qemu ram size detection
> Copyright 2008 Patrick Georgi
> Licensed under the terms of the GNU General Public License v2 or later
> */

Maybe nicer to have the same style on all comments?
> #include <types.h>
>  #include <console.h>
>  #include <device/device.h>
>  #include <device/pci.h>
>  #include <string.h>
> +#include <io.h>
>  #include "i440bx.h"
>  #include "statictree.h"
>
> /* Here are the ops for 440BX as a PCI domain. */
>
> +static int inb_cmos(int port)
> +{
> outb(port, 0x70);
> return inb(0x71);
>
> +}

Is this available somewhere else? Should it be?
> static void pci_domain_set_resources(struct device *dev)
>  {
>    struct device *mc_dev;
>    u32 tolmk;		/* Top of low mem, Kbytes. */
>    int idx;
> struct northbridge_intel_i440bxemulation_domain_config *device_configuration =
>    dev->device_configuration;
> tolmk = device_configuration->ramsize * 1024;
> /* read large mem memory descriptor
>   for <16 MB read the more detailed small mem descriptor
>   all values in kbytes */
> tolmk = ((inb_cmos(0x35)<<8) |inb_cmos(0x34)) * 64;
> if (tolmk <= 16 * 1024) {
> tolmk = (inb_cmos(0x31)<<8) |inb_cmos(0x30);
> }

I like this.

//Peter

[Patrick Georgi]

Peter Stuge schrieb:
> On Fri, Jun 06, 2008 at 11:01:06PM +0200, Patrick Georgi wrote:
> > ramsize = "128";
>
> Is this parameter now used anywhere else?

The only other reference for "ramsize" I find is doc/design/newboot.lyx, 
which was wrong on this already (I don't see any way to change that 
value via kconfig). Unfortunately I don't have lyx, and I fear that 
mangling that file into compliance by hand will only break it. How to go 
on there?
> Maybe nicer to have the same style on all comments?

Sorry, you're right. I added myself to the top header (which I didn't 
see before). I'll post a new patch when the other open issues are resolved.
> > +static int inb_cmos(int port)
> > +{
> > outb(port, 0x70);
> > return inb(0x71);
> >
> > +}
>
> Is this available somewhere else? Should it be?

It seems to be an official interface that bochs/qemu adopted for their 
purpose (nvramtool uses these ports, too), but I can't see any other use 
in cbv3 except nvramtool, which is userland.
It could (together with a write operation) be provided for future use. 
It might even be combined with nvramtool (but that's a different layer: 
boot code vs. userland, so I don't feel good with that).

In my opinion, moving them (two functions, read/write) as static 
functions to a header would be the best option. It's only drawn in when 
necessary, it's probably inlined anyway, and if they get used more 
regularily, we can still consider moving them to a separate source file 
in lib/. I'd look if that header could be used both for boot code and 
userland code, but not if that involves too many hacks.

Thanks for the review,
Patrick