On Fri, Jan 27, 2017 at 03:46:33PM +0100, Laszlo Ersek wrote: > On 01/27/17 15:18, Kevin O'Connor wrote: > > If an offset is going to be added, shouldn't both a source offset and > > destination offset be used? > > > > /* > > * COMMAND_WRITE_POINTER - update a writeable file named > > * @pointer.dest_file at @pointer.dest_offset, by writing pointer > > * plus @pointer.src_offset to the blob originating from > > * @src_file. 1,2,4 or 8 byte unsigned write is used depending > > * on @pointer.size. > > */ > > struct { > > char dest_file[BIOS_LINKER_LOADER_FILESZ]; > > char src_file[BIOS_LINKER_LOADER_FILESZ]; > > uint32_t src_offset, dest_offset; > > uint8_t size; > > } pointer; > > > > I doubt the offsets or size is really all that important though. > > The offset into the fw_cfg file that receives the allocation address is > important, that allows the same file to receive several different > addresses (for different downloaded blobs), at different offsets. > > OTOH, asking the firmware to add a constant to the address value before > writing it to the fw_cfg file is not necessary, in my opinion. The blob > that the firmware allocated and downloaded originates from QEMU to begin > with, so QEMU knows its internal structure.
I guess I'm missing why QEMU would want to use the same writable file for multiple pointers as well as why it would want support for pointers smaller than 8 bytes in size. If it's because it may be easier to support an internal QEMU blob of a particular format, then adding a src_offset would facilitate that. However, if it was done so that WRITE_POINTER mimicks ADD_POINTER then that's fine too. I'm okay with either format. -Kevin