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.
Current QEMU always load initrd below below_4g_mem_size which always
less than 4G, so here limit 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 f095725..5e2f83c 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)
struct e820_entry {
uint64_t address;
@@ -916,6 +917,17 @@ static void load_linux(PCMachineState *pcms,
} else {
initrd_max = 0x37ffffff;
}
+ if (protocol >= 0x20c) {
+ unsigned int xloadflags = lduw_p(header+0x236);
+ if (xloadflags & XLF_CAN_BE_LOADED_ABOVE_4G_MASK) {
+ /*
+ * Although kernel allow initrd loading to above 4G, here we
+ * limit initrd_max to 4G -1 due to current QEMU always loads
+ * initrd 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
