pc: Fix RTC CMOS info on RAM for ram_size < 1MiB

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>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Markus Armbruster 2012-08-15 13:12:20 +02:00 committed by Blue Swirl
parent ff96101552
commit e89001f72e

31
hw/pc.c
View file

@ -338,32 +338,37 @@ 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);
else
/* 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);