Re: [Qemu-devel] [PATCH 2/2] pc: Fix RTC CMOS info on RAM for ram_size < 1MiB

[Blue Swirl]

On Tue, Aug 14, 2012 at 11:58 AM, Markus Armbruster <address@hidden> 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 <address@hidden>
> ---
>  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
>