On Wed, Nov 21, 2018 at 10:06:06AM +0800, Li Zhijian wrote:
> a new field xloadflags was added to recent x86 linux, and BIT 1:
> XLF_CAN_BE_LOADED_ABOVE_4G is used to tell bootload that where initrd can be
> loaded saftly.
safely
>
> Current QEMU always load
loads
> initrd below below_4g_mem_size which
is
> always
> less than 4G, so here limit
limiting
> initrd_max to 4G - 1 simply is enough if
> this bit is set.
>
> CC: Paolo Bonzini <pbonz...@redhat.com>
> CC: Richard Henderson <r...@twiddle.net>
> CC: Eduardo Habkost <ehabk...@redhat.com>
> CC: "Michael S. Tsirkin" <m...@redhat.com>
> CC: Marcel Apfelbaum <marcel.apfelb...@gmail.com>
> Signed-off-by: Li Zhijian <lizhij...@cn.fujitsu.com>
> ---
> hw/i386/pc.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 2ffe6fb..6d4b973 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -92,6 +92,7 @@
> #define FW_CFG_HPET (FW_CFG_ARCH_LOCAL + 4)
>
> #define E820_NR_ENTRIES 16
> +#define XLF_CAN_BE_LOADED_ABOVE_4G_MASK (1 << 1)
why not XLF_CAN_BE_LOADED_ABOVE_4G to be consistent
with Linux?
In fact let's import include/uapi/asm/bootparam.h
into standard-headers, and use the macro from there?
>
> struct e820_entry {
> uint64_t address;
> @@ -916,6 +917,17 @@ static void load_linux(PCMachineState *pcms,
> } else {
> initrd_max = 0x37ffffff;
> }
> + if (protocol >= 0x20c) {
Let's move it above so we have
if (protocol >= 20c)
else if 0x203
else
> + unsigned int xloadflags = lduw_p(header+0x236);
> + if (xloadflags & XLF_CAN_BE_LOADED_ABOVE_4G_MASK) {
> + /*
> + * Although kernel allow
allows
> initrd loading to above 4G, here we
> + * limit initrd_max to 4G -1
Well not really, it just makes it as large as possible
while still staying below 4G.
> due to
since
> current QEMU always loads
> + * initrd
It's not QEMU, is it? It's actually the bios ...
> below pcms->below_4g_mem_size
> + */
> + initrd_max = UINT32_MAX;
> + }
> + }
>
> if (initrd_max >= pcms->below_4g_mem_size - pcmc->acpi_data_size) {
> initrd_max = pcms->below_4g_mem_size - pcmc->acpi_data_size - 1;
> --
> 2.7.4
