linux-kernel - Re: MPTable can not be high-memory on Linux

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Date:	Sat, 28 Feb 2009 18:41:28 -0500
From:	Kevin O'Connor <kevin@...onnor.net>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, "Rafael J. Wysocki" <rjw@...k.pl>,
	Stefan Reinauer <stepan@...esystems.de>,
	linux-kernel@...r.kernel.org, coreboot@...eboot.org,
	Jaswinder Singh Rajput <jaswinder@...radead.org>
Subject: Re: MPTable can not be high-memory on Linux

On Sun, Feb 22, 2009 at 10:14:56PM -0800, Yinghai Lu wrote:
> please check
> 
> [PATCH] x86: check physptr with max_low_pfn on 32bit

Thanks for looking at this issue.

Unfortunately, the kernel still does not work with the applied patch.
Neither 32bit nor 64bit kernels boot.  (Note, I applied the patch to
Linus' git, and I had to replace mpf->physptr with mpf->mpf_physptr.)

The error messages from before and after patching appear to be the
same.


In order to aid in testing, I modified SeaBIOS to force the mptable
into high memory even in qemu mode.  A modified bios.bin file can be
found at:

http://linuxtogo.org/~kevin/SeaBIOS/bios.bin-high-mptable

To use it with qemu, the steps are roughly:

mkdir testbios
cp /usr/share/qemu/*.bin testbios/
cp bios.bin-high-mptable testbios/bios.bin
qemu -L testbios/ -hda mytestlinux.img -serial file:mylog


The modified bios.bin can also be built manually by running:

git clone git://linuxtogo.org/home/kevin/seabios.git
cd seabios
patch -p1 < patch-from-below
make
cp out/bios.bin ../bios.bin-high-mptable

-Kevin


diff --git a/src/config.h b/src/config.h
index 56e5302..1ecc86f 100644
--- a/src/config.h
+++ b/src/config.h
@@ -21,7 +21,7 @@
 #define CONFIG_DEBUG_LEVEL 1
 
 // Send debugging information to serial port
-#define CONFIG_DEBUG_SERIAL 0
+#define CONFIG_DEBUG_SERIAL 1
 
 // Support for int13 floppy drive access
 #define CONFIG_FLOPPY_SUPPORT 1
@@ -77,7 +77,7 @@
 // Support finding a UUID (for smbios) via "magic" outl sequence.
 #define CONFIG_UUID_BACKDOOR 1
 // Support generation of ACPI tables (for emulators)
-#define CONFIG_ACPI 1
+#define CONFIG_ACPI 0
 // Support bios callbacks specific to via vgabios.
 #define CONFIG_VGAHOOKS 0
 // Support S3 resume handler.
diff --git a/src/mptable.c b/src/mptable.c
index 9e030fe..79cc7ba 100644
--- a/src/mptable.c
+++ b/src/mptable.c
@@ -19,7 +19,7 @@ mptable_init(void)
     dprintf(3, "init MPTable\n");
 
     int smp_cpus = smp_probe();
-    if (smp_cpus <= 1)
+    if (0 && smp_cpus <= 1)
         // Building an mptable on uniprocessor machines confuses some OSes.
         return;
 
@@ -39,7 +39,9 @@ mptable_init(void)
     /* floating pointer structure */
     struct mptable_floating_s *floating = (void*)start;
     memset(floating, 0, sizeof(*floating));
-    struct mptable_config_s *config = (void*)&floating[1];
+//    struct mptable_config_s *config = (void*)&floating[1];
+    struct mptable_config_s *config = (void*)(RamSize - 64*1024);
+    add_e820((u32)config, 64*1024, E820_RESERVED);
     floating->signature = MPTABLE_SIGNATURE;
     floating->physaddr = (u32)config;
     floating->length = 1;
--
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