Re: [RFC] Extending MTRRs above 4G

[Alex Williamson <alex.williamson@hp.com>]

On Wed, 2008-09-17 at 11:51 -0600, Alex Williamson wrote:
> the patch below is a possible
> approach to continue down this path and enlighten rombios32 about the
> real top of memory, and setup MTRRs appropriately.  It doesn't address
> SMBIOS or whatever causes grub to only report upper memory below 4G.

This version also fixes SMBIOS, I'm haven't found where grub is getting
it's idea of upper memory yet.  It seems like there's a bug in SMBIOS
type 19 & 20 entries that we were using (size_mb - 1) * 1024.  I changed
this to (size_mb * 1024) - 1, which seems to make a lot more sense in
the dmidecode output.  If that's wrong, please let me know.  Thanks,

Alex

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
--

diff --git a/bios/rombios32.c b/bios/rombios32.c
index 2dc1d25..f0cb070 100755
--- a/bios/rombios32.c
+++ b/bios/rombios32.c
@@ -415,7 +415,8 @@ int smp_cpus;
 uint32_t cpuid_signature;
 uint32_t cpuid_features;
 uint32_t cpuid_ext_features;
-unsigned long ram_size;
+unsigned long low_ram_size;
+uint64_t mem_top;
 uint8_t bios_uuid[16];
 #ifdef BX_USE_EBDA_TABLES
 unsigned long ebda_cur_addr;
@@ -503,12 +504,12 @@ void setup_mtrr(void)
 	return;
     u.val = 0;
     for (i = 0; i < 8; ++i)
-        if (ram_size >= 65536 * (i + 1))
+        if (low_ram_size >= 65536 * (i + 1))
             u.valb[i] = 6;
     wrmsr_smp(MSR_MTRRfix64K_00000, u.val);
     u.val = 0;
     for (i = 0; i < 8; ++i)
-        if (ram_size >= 65536 * 8 + 16384 * (i + 1))
+        if (low_ram_size >= 65536 * 8 + 16384 * (i + 1))
             u.valb[i] = 6;
     wrmsr_smp(MSR_MTRRfix16K_80000, u.val);
     wrmsr_smp(MSR_MTRRfix16K_A0000, 0);
@@ -522,9 +523,17 @@ void setup_mtrr(void)
     wrmsr_smp(MSR_MTRRfix4K_F8000, 0);
     vbase = 0;
     --vcnt; /* leave one mtrr for VRAM */
-    for (i = 0; i < vcnt && vbase < ram_size; ++i) {
+    for (i = 0; i < vcnt && vbase < low_ram_size; ++i) {
         vmask = (1ull << 40) - 1;
-        while (vbase + vmask + 1 > ram_size)
+        while (vbase + vmask + 1 > low_ram_size)
+            vmask >>= 1;
+        wrmsr_smp(MTRRphysBase_MSR(i), vbase | 6);
+        wrmsr_smp(MTRRphysMask_MSR(i), (~vmask & 0xfffffff000ull) | 0x800);
+        vbase += vmask + 1;
+    }
+    for (vbase = 1ull << 32; i < vcnt && vbase < mem_top; ++i) {
+        vmask = (1ull << 40) - 1;
+        while (vbase + vmask + 1 > mem_top)
             vmask >>= 1;
         wrmsr_smp(MTRRphysBase_MSR(i), vbase | 6);
         wrmsr_smp(MTRRphysMask_MSR(i), (~vmask & 0xfffffff000ull) | 0x800);
@@ -535,16 +544,26 @@ void setup_mtrr(void)
 
 void ram_probe(void)
 {
-  if (cmos_readb(0x34) | cmos_readb(0x35))
-    ram_size = (cmos_readb(0x34) | (cmos_readb(0x35) << 8)) * 65536 +
-        16 * 1024 * 1024;
-  else
-    ram_size = (cmos_readb(0x17) | (cmos_readb(0x18) << 8)) * 1024;
+    if (cmos_readb(0x34) | cmos_readb(0x35))
+        low_ram_size = (cmos_readb(0x34) | (cmos_readb(0x35) << 8)) *
+                       65536 + 16 * 1024 * 1024;
+    else
+        low_ram_size = (cmos_readb(0x17) | (cmos_readb(0x18) << 8)) * 1024;
+
+    if (cmos_readb(0x5b) | cmos_readb(0x5c) | cmos_readb(0x5d)) {
+        mem_top = ((uint64_t)cmos_readb(0x5b) << 16) |
+                  ((uint64_t)cmos_readb(0x5c) << 24) |
+                  ((uint64_t)cmos_readb(0x5d) << 32);
+        mem_top += 1ull << 32;
+    } else
+        mem_top = low_ram_size;
+
 #ifdef BX_USE_EBDA_TABLES
     ebda_cur_addr = ((*(uint16_t *)(0x40e)) << 4) + 0x380;
 #endif
-    BX_INFO("ram_size=0x%08lx\n", ram_size);
-  setup_mtrr();
+    BX_INFO("low_ram_size=0x%08lx\n", low_ram_size);
+    BX_INFO("top of ram %ldMB\n", mem_top / (1024 * 1024));
+    setup_mtrr();
 }
 
 /****************************************************/
@@ -951,7 +970,7 @@ void pci_bios_init(void)
 {
     pci_bios_io_addr = 0xc000;
     pci_bios_mem_addr = 0xf0000000;
-    pci_bios_bigmem_addr = ram_size;
+    pci_bios_bigmem_addr = low_ram_size;
     if (pci_bios_bigmem_addr < 0x90000000)
         pci_bios_bigmem_addr = 0x90000000;
 
@@ -1021,7 +1040,7 @@ static void mptable_init(void)
     int mp_config_table_size;
 
 #ifdef BX_USE_EBDA_TABLES
-    mp_config_table = (uint8_t *)(ram_size - ACPI_DATA_SIZE - MPTABLE_MAX_SIZE);
+    mp_config_table = (uint8_t *)(low_ram_size - ACPI_DATA_SIZE - MPTABLE_MAX_SIZE);
 #else
     bios_table_cur_addr = align(bios_table_cur_addr, 16);
     mp_config_table = (uint8_t *)bios_table_cur_addr;
@@ -1409,7 +1428,7 @@ void acpi_bios_init(void)
     bios_table_cur_addr += sizeof(*rsdp);
 #endif
 
-    addr = base_addr = ram_size - ACPI_DATA_SIZE;
+    addr = base_addr = low_ram_size - ACPI_DATA_SIZE;
     rsdt_addr = addr;
     rsdt = (void *)(addr);
     addr += sizeof(*rsdt);
@@ -1931,7 +1950,7 @@ smbios_type_19_init(void *start, uint32_t memory_size_mb)
     p->header.handle = 0x1300;
 
     p->starting_address = 0;
-    p->ending_address = (memory_size_mb-1) * 1024;
+    p->ending_address = (memory_size_mb * 1024) - 1;
     p->memory_array_handle = 0x1000;
     p->partition_width = 1;
 
@@ -1952,7 +1971,7 @@ smbios_type_20_init(void *start, uint32_t memory_size_mb)
     p->header.handle = 0x1400;
 
     p->starting_address = 0;
-    p->ending_address = (memory_size_mb-1)*1024;
+    p->ending_address = (memory_size_mb * 1024) - 1;
     p->memory_device_handle = 0x1100;
     p->memory_array_mapped_address_handle = 0x1300;
     p->partition_row_position = 1;
@@ -2003,7 +2022,7 @@ void smbios_init(void)
 {
     unsigned cpu_num, nr_structs = 0, max_struct_size = 0;
     char *start, *p, *q;
-    int memsize = ram_size / (1024 * 1024);
+    int memsize = (mem_top - (1ull << 32) + low_ram_size) / (1024 * 1024);
 
 #ifdef BX_USE_EBDA_TABLES
     ebda_cur_addr = align(ebda_cur_addr, 16);
@@ -2030,8 +2049,8 @@ void smbios_init(void)
         add_struct(smbios_type_4_init(p, cpu_num));
     add_struct(smbios_type_16_init(p, memsize));
     add_struct(smbios_type_17_init(p, memsize));
-    add_struct(smbios_type_19_init(p, memsize));
-    add_struct(smbios_type_20_init(p, memsize));
+    add_struct(smbios_type_19_init(p, mem_top / (1024 * 1024)));
+    add_struct(smbios_type_20_init(p, mem_top / (1024 * 1024)));
     add_struct(smbios_type_32_init(p));
     add_struct(smbios_type_127_init(p));