path: root/pc-bios
diff options
authorPaolo Bonzini <pbonzini@redhat.com>2014-12-11 02:17:03 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2014-12-15 12:21:03 +0100
commit269e2358492b674c50160553d037702e916b9f1b (patch)
tree3b04d961c85678cc0f5afa45fb6bca7c3aa9a74b /pc-bios
parent575a6f4082c45778b93032ef1e7fbea4467b3a2a (diff)
linuxboot: fix loading old kernels
Old kernels that used high memory only allowed the initrd to be in the first 896MB of memory. If you load the initrd above, they complain that "initrd extends beyond end of memory". In order to fix this, while not breaking machines with small amounts of memory fixed by cdebec5 (linuxboot: compute initrd loading address, 2014-10-06), we need to distinguish two cases. If pc.c placed the initrd at end of memory, use the new algorithm based on the e801 memory map. If instead pc.c placed the initrd at the maximum address specified by the bzImage, leave it there. The only interesting part is that the low-memory info block is now loaded very early, in real mode, and thus the 32-bit address has to be converted into a real mode segment. The initrd address is also patched in the info block before entering real mode, it is simpler that way. This fixes booting the RHEL4.8 32-bit installation image with 1GB of RAM. Cc: qemu-stable@nongnu.org Cc: mst@redhat.com Cc: jsnow@redhat.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'pc-bios')
-rw-r--r--pc-bios/linuxboot.binbin1024 -> 1024 bytes
2 files changed, 27 insertions, 10 deletions
diff --git a/pc-bios/linuxboot.bin b/pc-bios/linuxboot.bin
index 130103fb73..923d1796fb 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 5bc0af08e0..ba821ab922 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -76,7 +76,31 @@ boot_kernel:
- /* Compute initrd address */
+ /* Read info block in low memory (0x10000 or 0x90000) */
+ shr $4, %eax
+ mov %eax, %es
+ xor %edi, %edi
+ read_fw_blob_addr32_edi(FW_CFG_SETUP)
+ cmpw $0x203, %es:0x206 // if protocol >= 0x203
+ jae 1f // have initrd_max
+ movl $0x37ffffff, %es:0x22c // else assume 0x37ffffff
+ /* Check if using kernel-specified initrd address */
+ mov %eax, %edi // (load_kernel wants it in %edi)
+ read_fw FW_CFG_INITRD_SIZE // find end of initrd
+ add %edi, %eax
+ xor %es:0x22c, %eax // if it matches es:0x22c
+ and $-4096, %eax // (apart from padding for page)
+ jz load_kernel // then initrd is not at top
+ // of memory
+ /* pc.c placed the initrd at end of memory. Compute a better
+ * initrd address based on e801 data.
+ */
mov $0xe801, %ax
xor %cx, %cx
xor %dx, %dx
@@ -107,7 +131,9 @@ copy_kernel:
subl %eax, %edi
andl $-4096, %edi /* EDI = start of initrd */
+ movl %edi, %es:0x218 /* put it in the header */
/* 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. */
@@ -139,19 +165,10 @@ copy_kernel:
/* We're now running in 16-bit CS, but 32-bit ES! */
/* Load kernel and initrd */
- pushl %edi
- 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
mov %eax, %cr0