Hi,
while trying to run x286emul with kernel 2.2.10 I discovered a change in
ldt handling of the kernel in arch/i386/kernel/ldt.c :
For a process without ldt, the first modify_ldt(0,...) did return the
default_ldt containing the lcall7 call gate in slot 0 with kernels 2.0.x and
2.1.x (at least up to x = 76 ).
Kernel 2.2.x returns an empty ldt. After loading of the binary by binfmt_xout.c
there is a slot 0 in the ldt but it does not contain the call gate.
I changed arch/i386/kernel/ldt.c to the old behaviour (see patch ) and x286emul
is working.
Now I wonder, if this is a feature or a bug in kernel 2.2.x and if it is a
feature, is it safe to apply my patch?
Joerg
*** arch/i386/kernel/ldt.c Sun Sep 13 21:16:22 1998
--- ../linux-2.2.10a/arch/i386/kernel/ldt.c Sun Jul 4 16:07:13 1999
*************** static int read_ldt(void * ptr, unsigned
*** 24,32 ****
if (!ptr)
return -EINVAL;
- if (!address)
- return 0;
size = LDT_ENTRIES*LDT_ENTRY_SIZE;
if (size > bytecount)
size = bytecount;
return copy_to_user(ptr, address, size) ? -EFAULT : size;
--- 24,36 ----
if (!ptr)
return -EINVAL;
size = LDT_ENTRIES*LDT_ENTRY_SIZE;
+ if (!address)
+ /* joerg return 0; */
+ {
+ address = &default_ldt;
+ size = sizeof(default_ldt);
+ }
if (size > bytecount)
size = bytecount;
return copy_to_user(ptr, address, size) ? -EFAULT : size;
--
------------------------------------------------------------------------------
Joerg Ahrens _/
Koenigsberger Strasse 32 _/_/
31226 Peine _/ _/
Tel.: 05171/57308 _/ _/_/_/_/
e-mail: [EMAIL PROTECTED] _/_/_/_/ _/
------------------------------------------------------------------------------
