Recent GCC compiles linuxboot_dma.c to 921 bytes, while CentOS 6 needs
1029 and clang needs 1527. Because the size of the ROM, rounded to the
next 512 bytes, must match, this causes the API to break between a <1K
ROM and one that is bigger.
We want to make the ROM 1.5 KB in size, but it's better to make clang
produce leaner ROMs, because currently it is worryingly close to the limit.
To fix this prevent clang's happy inlining (which -Os cannot prevent).
This only requires adding a noinline attribute.
Second, the patch makes sure that the ROM has enough padding to prevent
ABI breakage on different compilers. The size is now hardcoded in the file
that is passed to signrom.py, as was the case before commit 6f71b77
("scripts/signrom.py: Allow option ROM checksum script to write the size
header.", 2016-05-23); signrom.py however will still pad the input to
the requested size. This ensures that the padding goes beyond the
next multiple of 512 if necessary, and also avoids the need for
-fno-toplevel-reorder which clang doesn't support. signrom.py can then
error out if the requested size is too small for the actual size of the
compiled ROM.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Because of the risk that compilers might not emit the asm() block at
the beginning of the option ROM, check that the ROM contains the
required magic signature.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <1463000807-18015-3-git-send-email-rjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Modify the signrom.py script so that if the size byte in the header is
0 (ie. not set) then the script will set the size. If the size byte
is non-zero then we do the same as before, so this doesn't require
changes to any existing ROM sourcecode.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Message-Id: <1463000807-18015-2-git-send-email-rjones@redhat.com>
Now that we have a hard dependency on python anyway, we can replace the
slow shell script to calculate the option ROM checksum with a fast AND
portable python version. Tested both with python 2.7 and 3.1.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Paolo Bonzini