On Mon, Oct 05, 2015 at 08:43:46AM -0400, Gabriel L. Somlo wrote: > On Mon, Oct 05, 2015 at 01:23:33PM +0100, Mark Rutland wrote: > > On Mon, Oct 05, 2015 at 01:48:52PM +0200, Paolo Bonzini wrote: > > > > > > > > > On 05/10/2015 12:00, Mark Rutland wrote: > > > > Some of the keys in the example look like they'd come from other sources > > > > (e.g. the *-tables entries), while others look like kernel/bootloader > > > > configuration options (e.g. etc/boot-fail-wait, bootorder) -- I'm > > > > concerned about redundancy here. > > > > > > The redundancy is because the firmware and the bootloader actually > > > _consume_ these fw_cfg strings to produce the others (the ACPI tables, > > > the kernel configuration options). > > > > > > On the other hand, hiding some strings just because they ought to have > > > been consumed already makes little sense. > > > > Sure. However, I'm concerned that providing redundant interfaces for > > those could lead to people grabbing information from here (because it's > > convenient) rather than the existing canonical locations, which means we > > get more software that works on fewer systems for no good reason. > > > > What I couldn't figure out was what _additional_ information this > > provided; it looked like a mixed bag of details we could already get > > from disparate sources. If that's all it does, then it seems to me like > > it doesn't add any benefit and potentially makes things worse. > > > > So what do we get from this interface that we cannot get elsewhere, and > > why is this the best way of exposing it? > > Starting with qemu 2.4, it is possible to insert arbitrary named > blobs into fw_cfg from the qemu command line. *Those* entries > might be interesting to userspace, which is why it might be handy > to access to fw_cfg blobs in general. So this is a mechanism to pass arbitrary key:value pairs to a guest userspace? What would those be used for, and why would this be the correct location for that? How do we avoid clashes between user-selected names and those we need to pass actual FW data? Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
