aboutsummaryrefslogtreecommitdiff
path: root/pc-bios
diff options
context:
space:
mode:
authorPaolo Bonzini <pbonzini@redhat.com>2014-10-06 16:49:57 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2014-10-09 15:36:15 +0200
commitcdebec5e40bd0af82da0659f37af85ee2aa2c9d1 (patch)
tree7e355ce31516dbd959a49639e6f2ed15f6cb6e6f /pc-bios
parentfc02086b5ab8de50ce8234cf8f42b254de9e5d91 (diff)
downloadqemu-arm-cdebec5e40bd0af82da0659f37af85ee2aa2c9d1.tar.gz
linuxboot: compute initrd loading address
Even though hw/i386/pc.c tries to compute a valid loading address for the initrd, close to the top of RAM, this does not take into account other data that is malloced into that memory by SeaBIOS. Luckily we can easily look at the memory map to find out how much memory is used up there. This patch places the initrd in the first four gigabytes, below the first hole (as returned by INT 15h, AX=e801h). Without this patch: [ 0.000000] init_memory_mapping: [mem 0x07000000-0x07fdffff] [ 0.000000] RAMDISK: [mem 0x0710a000-0x07fd7fff] With this patch: [ 0.000000] init_memory_mapping: [mem 0x07000000-0x07fdffff] [ 0.000000] RAMDISK: [mem 0x07112000-0x07fdffff] So linuxboot is able to use the 64k that were added as padding for QEMU <= 2.1. Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'pc-bios')
-rw-r--r--pc-bios/linuxboot.binbin1024 -> 1024 bytes
-rw-r--r--pc-bios/optionrom/linuxboot.S47
-rw-r--r--pc-bios/optionrom/optionrom.h21
3 files changed, 61 insertions, 7 deletions
diff --git a/pc-bios/linuxboot.bin b/pc-bios/linuxboot.bin
index e7c36694f9..130103fb73 100644
--- a/pc-bios/linuxboot.bin
+++ b/pc-bios/linuxboot.bin
Binary files differ
diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
index 748c831160..5bc0af08e0 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -76,14 +76,45 @@ boot_kernel:
copy_kernel:
+ /* Compute initrd address */
+ mov $0xe801, %ax
+ xor %cx, %cx
+ xor %dx, %dx
+ int $0x15
+
+ /* Output could be in AX/BX or CX/DX */
+ or %cx, %cx
+ jnz 1f
+ or %dx, %dx
+ jnz 1f
+ mov %ax, %cx
+ mov %bx, %dx
+1:
+
+ or %dx, %dx
+ jnz 2f
+ addw $1024, %cx /* add 1 MB */
+ movzwl %cx, %edi
+ shll $10, %edi /* convert to bytes */
+ jmp 3f
+
+2:
+ addw $16777216 >> 16, %dx /* add 16 MB */
+ movzwl %dx, %edi
+ shll $16, %edi /* convert to bytes */
+
+3:
+ read_fw FW_CFG_INITRD_SIZE
+ subl %eax, %edi
+ andl $-4096, %edi /* EDI = start of initrd */
/* We need to load the kernel into memory we can't access in 16 bit
mode, so let's get into 32 bit mode, write the kernel and jump
back again. */
/* Reserve space on the stack for our GDT descriptor. */
- mov %esp, %ebp
- sub $16, %esp
+ mov %esp, %ebp
+ sub $16, %esp
/* Now create the GDT descriptor */
movw $((3 * 8) - 1), -16(%bp)
@@ -108,10 +139,18 @@ copy_kernel:
/* We're now running in 16-bit CS, but 32-bit ES! */
/* Load kernel and initrd */
+ pushl %edi
+ read_fw_blob_addr32_edi(FW_CFG_INITRD)
read_fw_blob_addr32(FW_CFG_KERNEL)
- read_fw_blob_addr32(FW_CFG_INITRD)
read_fw_blob_addr32(FW_CFG_CMDLINE)
- read_fw_blob_addr32(FW_CFG_SETUP)
+
+ read_fw FW_CFG_SETUP_ADDR
+ mov %eax, %edi
+ mov %eax, %ebx
+ read_fw_blob_addr32_edi(FW_CFG_SETUP)
+
+ /* Update the header with the initrd address we chose above */
+ popl %es:0x218(%ebx)
/* And now jump into Linux! */
mov $0, %eax
diff --git a/pc-bios/optionrom/optionrom.h b/pc-bios/optionrom/optionrom.h
index ce436085d9..f1a9021ec1 100644
--- a/pc-bios/optionrom/optionrom.h
+++ b/pc-bios/optionrom/optionrom.h
@@ -51,8 +51,6 @@
.endm
#define read_fw_blob_pre(var) \
- read_fw var ## _ADDR; \
- mov %eax, %edi; \
read_fw var ## _SIZE; \
mov %eax, %ecx; \
mov $var ## _DATA, %ax; \
@@ -68,6 +66,8 @@
* Clobbers: %eax, %edx, %es, %ecx, %edi
*/
#define read_fw_blob(var) \
+ read_fw var ## _ADDR; \
+ mov %eax, %edi; \
read_fw_blob_pre(var); \
/* old as(1) doesn't like this insn so emit the bytes instead: \
rep insb (%dx), %es:(%edi); \
@@ -80,7 +80,22 @@
*
* Clobbers: %eax, %edx, %es, %ecx, %edi
*/
-#define read_fw_blob_addr32(var) \
+#define read_fw_blob_addr32(var) \
+ read_fw var ## _ADDR; \
+ mov %eax, %edi; \
+ read_fw_blob_pre(var); \
+ /* old as(1) doesn't like this insn so emit the bytes instead: \
+ addr32 rep insb (%dx), %es:(%edi); \
+ */ \
+ .dc.b 0x67,0xf3,0x6c
+
+/*
+ * Read a blob from the fw_cfg device in forced addr32 mode, address is in %edi.
+ * Requires _SIZE and _DATA values for the parameter.
+ *
+ * Clobbers: %eax, %edx, %edi, %es, %ecx
+ */
+#define read_fw_blob_addr32_edi(var) \
read_fw_blob_pre(var); \
/* old as(1) doesn't like this insn so emit the bytes instead: \
addr32 rep insb (%dx), %es:(%edi); \