Hi!
Using gdbserver inside an UML instance displays "Couldn't write
debug
register". I have discovered this patch from Barry Friedman which
works
fine for me:
http://www.mail-archive.com/user-mode-linux-devel@lists.sourceforge.net/msg06753.html
Here is a rebased version of this patch:
diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c
index 3b52bf0..583070c 100644
--- a/arch/x86/um/ptrace_64.c
+++ b/arch/x86/um/ptrace_64.c
@@ -120,7 +120,7 @@ int poke_user(struct task_struct *child, long addr, long data)
else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
(addr <= offsetof(struct user, u_debugreg[7]))) {
addr -= offsetof(struct user, u_debugreg[0]);
- addr = addr >> 2;
+ addr = addr >> 3;
if ((addr == 4) || (addr == 5))
return -EIO;
child->thread.arch.debugregs[addr] = data;
@@ -187,7 +187,7 @@ int peek_user(struct task_struct *child, long addr, long data)
else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
(addr <= offsetof(struct user, u_debugreg[7]))) {
addr -= offsetof(struct user, u_debugreg[0]);
- addr = addr >> 2;
+ addr = addr >> 3;
tmp = child->thread.arch.debugregs[addr];
}
return put_user(tmp, (unsigned long *) data);
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