On Tue, Nov 16, 2010 at 7:22 AM, Gleb Natapov <gleb@xxxxxxxxxx> wrote: > On Mon, Nov 15, 2010 at 09:52:19PM -0500, Kevin O'Connor wrote: >> On Mon, Nov 15, 2010 at 03:36:25PM +0200, Gleb Natapov wrote: >> > On Mon, Nov 15, 2010 at 08:26:35AM -0500, Kevin O'Connor wrote: >> > > On Mon, Nov 15, 2010 at 09:40:08AM +0200, Gleb Natapov wrote: >> > > > On Sun, Nov 14, 2010 at 10:40:33PM -0500, Kevin O'Connor wrote: >> > > > > Why not just return a newline separated list that is null terminated? >> > > > > >> > > > Doing it like this will needlessly complicate firmware side. How do you >> > > > know how much memory to allocate before reading device list? >> > > >> > > My preference would be for the size to be exposed via the >> > > QEMU_CFG_FILE_DIR selector. Â(My preference would be for all objects >> > > in fw_cfg to have entries in QEMU_CFG_FILE_DIR describing their size >> > > in a reliable manner.) >> > > >> > Will interface suggested by Blue will be good for you? The one with two >> > fw_cfg ids. BOOTINDEX_LEN for len and BOOTINDEX_DATA for device list. I >> >> I dislike how different fw_cfg objects pass the length in different >> ways (eg, QEMU_CFG_E820_TABLE passes length as first 4 bytes). ÂThis >> is a common problem - I'd prefer if we could adopt one uniform way of >> passing length. ÂI think QEMU_CFG_FILE_DIR solves this problem well. >> > Looking at available fw cfg option I see that _SIZE _DATA is also a > common pattern. The problem with QEMU_CFG_FILE_DIR is that we have very > little available slots right now. If we a going to require everything to > use it we better grow number of available slots considerably now while > it is easily done (no option defined above file slots yet). FW_CFG_FILE_DIR seems to be a bit poorly designed. Maybe we should deprecate it and design a more scalable model. There are also string variables passed to BIOS (-prom-env for Sparc/PPC) which could then use this new model instead of NVRAM. > I personally do not have preferences one way or the other. Blue are you > OK with using QEMU_CFG_FILE_DIR? That would also work. >> I also have an ulterior motive here. ÂIf the boot order is exposed as >> a newline separated list via an entry in QEMU_CFG_FILE_DIR, then this >> becomes free for coreboot users as well. Â(On coreboot, the boot order >> could be placed in a "file" in flash with no change to the seabios >> code.) >> > You can define get_boot_order() function and implement it differently > for qemu and coreboot. For coreboot it will be one linear. Just call > cbfs_copyfile("bootorder"). BTW why newline separation is important? Newline and zero are both OK since neither can appear inside a valid boot path. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html