On Thu, Nov 29, 2018 at 05:37:45PM +0000, Rob Bradford wrote:
> If there is a QEMU FW CFG variable for memory available then always use
> it instead of CMOS. We cannot extract the values from E820 tables yet as
> that code assumes a working malloc.
Failed in testing.
Try a guest with 4G RAM, seabios falls back to cmos.
Try a guest with q35 and 7G RAM, seabios thinks it has 3G of low mem
even though it actually has 2G only.
> + // Prefer QEMU FW CFG entry over CMOS for initial RAM sizes
> + if (qemu_cfg_enabled()) {
> + qemu_cfg_read_entry(&RamSize, 0x03, sizeof(RamSize));
> + if (RamSize > 0) {
> + e820_add(0, RamSize, E820_RAM);
> + dprintf(1, "RamSize: 0x%08x [fw_cfg]\n", RamSize);
> + }
> + }
You are loosing the high bits here, RamSize is a 32bit variable.
Another problem is that you only get the total amout of memory here, not
the mapping.
I think there is no way around scanning the e820 table (etc/e830 fw_cfg
file) for the ram entry with the zero start address to figure the amout
of ram you have below 4G.
cheers,
Gerd
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