[Xen-changelog] [xen master] x86/boot: use %ecx instead of %eax

[patchbot@xxxxxxx]

commit 8bc02b47e5833c374b35618729d147d2980d4e05
Author:     Daniel Kiper <daniel.kiper@xxxxxxxxxx>
AuthorDate: Thu Aug 25 14:03:24 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Aug 25 14:03:24 2016 +0200

    x86/boot: use %ecx instead of %eax
    
    Use %ecx instead of %eax to store low memory upper limit from EBDA.
    This way we do not wipe multiboot protocol identifier. It is needed
    in reloc() to differentiate between multiboot (v1) and
    multiboot2 protocol.
    
    Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 xen/arch/x86/boot/head.S | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index 5538a4b..6f2c668 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -87,14 +87,14 @@ __start:
         jne     not_multiboot
 
         /* Set up trampoline segment 64k below EBDA */
-        movzwl  0x40e,%eax          /* EBDA segment */
-        cmp     $0xa000,%eax        /* sanity check (high) */
+        movzwl  0x40e,%ecx          /* EBDA segment */
+        cmp     $0xa000,%ecx        /* sanity check (high) */
         jae     0f
-        cmp     $0x4000,%eax        /* sanity check (low) */
+        cmp     $0x4000,%ecx        /* sanity check (low) */
         jae     1f
 0:
-        movzwl  0x413,%eax          /* use base memory size on failure */
-        shl     $10-4,%eax
+        movzwl  0x413,%ecx          /* use base memory size on failure */
+        shl     $10-4,%ecx
 1:
         /*
          * Compare the value in the BDA with the information from the
@@ -106,20 +106,20 @@ __start:
         cmp     $0x100,%edx         /* is the multiboot value too small? */
         jb      2f                  /* if so, do not use it */
         shl     $10-4,%edx
-        cmp     %eax,%edx           /* compare with BDA value */
-        cmovb   %edx,%eax           /* and use the smaller */
+        cmp     %ecx,%edx           /* compare with BDA value */
+        cmovb   %edx,%ecx           /* and use the smaller */
 
 2:      /* Reserve 64kb for the trampoline */
-        sub     $0x1000,%eax
+        sub     $0x1000,%ecx
 
         /* From arch/x86/smpboot.c: start_eip had better be page-aligned! */
-        xor     %al, %al
-        shl     $4, %eax
-        mov     %eax,sym_phys(trampoline_phys)
+        xor     %cl, %cl
+        shl     $4, %ecx
+        mov     %ecx,sym_phys(trampoline_phys)
 
         /* Save the Multiboot info struct (after relocation) for later use. */
         mov     $sym_phys(cpu0_stack)+1024,%esp
-        push    %eax                /* Boot trampoline address. */
+        push    %ecx                /* Boot trampoline address. */
         push    %ebx                /* Multiboot information address. */
         call    reloc
         mov     %eax,sym_phys(multiboot_ptr)
--
generated by git-patchbot for /home/xen/git/xen.git#master

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
https://lists.xenproject.org/xen-changelog