Patchwork [2/2] pc: Fix RTC CMOS info on RAM for ram_size < 1MiB

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Submitter Markus Armbruster
Date Aug. 14, 2012, 11:58 a.m.
Message ID <1344945535-2774-3-git-send-email-armbru@redhat.com>
Download mbox | patch
Permalink /patch/177237/
State New
Headers show

Comments

Markus Armbruster - Aug. 14, 2012, 11:58 a.m.
pc_cmos_init() always claims 640KiB base memory, and ram_size - 1MiB
extended memory.  The latter can underflow to "lots of extended
memory".  Fix both, and clean up some.

Note: SeaBIOS currently requires 1MiB of RAM, and doesn't check
whether it got enough.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 hw/pc.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)
Blue Swirl - Aug. 14, 2012, 6:31 p.m.
On Tue, Aug 14, 2012 at 11:58 AM, Markus Armbruster <armbru@redhat.com> wrote:
> pc_cmos_init() always claims 640KiB base memory, and ram_size - 1MiB
> extended memory.  The latter can underflow to "lots of extended
> memory".  Fix both, and clean up some.
>
> Note: SeaBIOS currently requires 1MiB of RAM, and doesn't check
> whether it got enough.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  hw/pc.c | 27 +++++++++++++++------------
>  1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/hw/pc.c b/hw/pc.c
> index e8bcfc0..1597fe6 100644
> --- a/hw/pc.c
> +++ b/hw/pc.c
> @@ -337,32 +337,35 @@ void pc_cmos_init(ram_addr_t ram_size, ram_addr_t above_4g_mem_size,
>      /* various important CMOS locations needed by PC/Bochs bios */
>
>      /* memory size */
> -    val = 640; /* base memory in K */
> +    /* base memory (first MiB) */
> +    val = MIN(ram_size / 1024, 640);
>      rtc_set_memory(s, 0x15, val);
>      rtc_set_memory(s, 0x16, val >> 8);
> -
> -    val = (ram_size / 1024) - 1024;
> +    /* extended memory (next 64MiB) */
> +    if (ram_size > 1024 * 1024)

Please add braces.

> +        val = (ram_size - 1024 * 1024) / 1024;
> +    else
> +        val = 0;
>      if (val > 65535)
>          val = 65535;
>      rtc_set_memory(s, 0x17, val);
>      rtc_set_memory(s, 0x18, val >> 8);
>      rtc_set_memory(s, 0x30, val);
>      rtc_set_memory(s, 0x31, val >> 8);
> -
> -    if (above_4g_mem_size) {
> -        rtc_set_memory(s, 0x5b, (unsigned int)above_4g_mem_size >> 16);
> -        rtc_set_memory(s, 0x5c, (unsigned int)above_4g_mem_size >> 24);
> -        rtc_set_memory(s, 0x5d, (uint64_t)above_4g_mem_size >> 32);
> -    }
> -
> -    if (ram_size > (16 * 1024 * 1024))
> -        val = (ram_size / 65536) - ((16 * 1024 * 1024) / 65536);
> +    /* memory between 16MiB and 4GiB */
> +    if (ram_size > 16 * 1024 * 1024)

Also here.

> +        val = (ram_size - 16 * 1024 * 1024) / 65536;
>      else
>          val = 0;
>      if (val > 65535)
>          val = 65535;
>      rtc_set_memory(s, 0x34, val);
>      rtc_set_memory(s, 0x35, val >> 8);
> +    /* memory above 4GiB */
> +    val = above_4g_mem_size / 65536;
> +    rtc_set_memory(s, 0x5b, val);
> +    rtc_set_memory(s, 0x5c, val >> 8);
> +    rtc_set_memory(s, 0x5d, val >> 16);
>
>      /* set the number of CPU */
>      rtc_set_memory(s, 0x5f, smp_cpus - 1);
> --
> 1.7.11.2
>
Markus Armbruster - Aug. 15, 2012, 8:23 a.m.
Blue Swirl <blauwirbel@gmail.com> writes:

> On Tue, Aug 14, 2012 at 11:58 AM, Markus Armbruster <armbru@redhat.com> wrote:
>> pc_cmos_init() always claims 640KiB base memory, and ram_size - 1MiB
>> extended memory.  The latter can underflow to "lots of extended
>> memory".  Fix both, and clean up some.
>>
>> Note: SeaBIOS currently requires 1MiB of RAM, and doesn't check
>> whether it got enough.
>>
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> ---
>>  hw/pc.c | 27 +++++++++++++++------------
>>  1 file changed, 15 insertions(+), 12 deletions(-)
>>
>> diff --git a/hw/pc.c b/hw/pc.c
>> index e8bcfc0..1597fe6 100644
>> --- a/hw/pc.c
>> +++ b/hw/pc.c
>> @@ -337,32 +337,35 @@ void pc_cmos_init(ram_addr_t ram_size, ram_addr_t above_4g_mem_size,
>>      /* various important CMOS locations needed by PC/Bochs bios */
>>
>>      /* memory size */
>> -    val = 640; /* base memory in K */
>> +    /* base memory (first MiB) */
>> +    val = MIN(ram_size / 1024, 640);
>>      rtc_set_memory(s, 0x15, val);
>>      rtc_set_memory(s, 0x16, val >> 8);
>> -
>> -    val = (ram_size / 1024) - 1024;
>> +    /* extended memory (next 64MiB) */
>> +    if (ram_size > 1024 * 1024)
>
> Please add braces.

Done in v2.

[...]

Patch

diff --git a/hw/pc.c b/hw/pc.c
index e8bcfc0..1597fe6 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -337,32 +337,35 @@  void pc_cmos_init(ram_addr_t ram_size, ram_addr_t above_4g_mem_size,
     /* various important CMOS locations needed by PC/Bochs bios */
 
     /* memory size */
-    val = 640; /* base memory in K */
+    /* base memory (first MiB) */
+    val = MIN(ram_size / 1024, 640);
     rtc_set_memory(s, 0x15, val);
     rtc_set_memory(s, 0x16, val >> 8);
-
-    val = (ram_size / 1024) - 1024;
+    /* extended memory (next 64MiB) */
+    if (ram_size > 1024 * 1024)
+        val = (ram_size - 1024 * 1024) / 1024;
+    else
+        val = 0;
     if (val > 65535)
         val = 65535;
     rtc_set_memory(s, 0x17, val);
     rtc_set_memory(s, 0x18, val >> 8);
     rtc_set_memory(s, 0x30, val);
     rtc_set_memory(s, 0x31, val >> 8);
-
-    if (above_4g_mem_size) {
-        rtc_set_memory(s, 0x5b, (unsigned int)above_4g_mem_size >> 16);
-        rtc_set_memory(s, 0x5c, (unsigned int)above_4g_mem_size >> 24);
-        rtc_set_memory(s, 0x5d, (uint64_t)above_4g_mem_size >> 32);
-    }
-
-    if (ram_size > (16 * 1024 * 1024))
-        val = (ram_size / 65536) - ((16 * 1024 * 1024) / 65536);
+    /* memory between 16MiB and 4GiB */
+    if (ram_size > 16 * 1024 * 1024)
+        val = (ram_size - 16 * 1024 * 1024) / 65536;
     else
         val = 0;
     if (val > 65535)
         val = 65535;
     rtc_set_memory(s, 0x34, val);
     rtc_set_memory(s, 0x35, val >> 8);
+    /* memory above 4GiB */
+    val = above_4g_mem_size / 65536;
+    rtc_set_memory(s, 0x5b, val);
+    rtc_set_memory(s, 0x5c, val >> 8);
+    rtc_set_memory(s, 0x5d, val >> 16);
 
     /* set the number of CPU */
     rtc_set_memory(s, 0x5f, smp_cpus - 1);