On Mon, Oct 25, 2021 at 08:20:05AM -0500, Patrick Williams wrote: > On Mon, Oct 25, 2021 at 03:58:25PM +0300, Andy Shevchenko wrote: > > On Mon, Oct 25, 2021 at 06:44:26AM -0500, Patrick Williams wrote: > > > On Mon, Oct 25, 2021 at 08:15:41AM +0200, Greg Kroah-Hartman wrote: > > > > On Mon, Oct 25, 2021 at 12:38:08AM -0500, Frank Rowand wrote: > > > > > On 10/23/21 3:56 AM, Greg Kroah-Hartman wrote: > > > > > > > We have the bind/unbind ability today, from userspace, that can control > > > > this. Why not just have Linux grab the device when it boots, and then > > > > when userspace wants to "give the device up", it writes to "unbind" in > > > > sysfs, and then when all is done, it writes to the "bind" file and then > > > > Linux takes back over. > > > > > > > > Unless for some reason Linux should _not_ grab the device when booting, > > > > then things get messier, as we have seen in this thread. > > > > > > This is probably more typical on a BMC than atypical. The systems often require > > > the BMC (running Linux) to be able to reboot independently from the managed host > > > (running anything). In the example Zev gave, the BMC rebooting would rip away > > > the BIOS chip from the running host. > > > > > > The BMC almost always needs to come up in a "I don't know what could possibly be > > > going on in the system" state and re-discover where the system was left off. > > > > Isn't it an architectural issue then? > > I'm not sure what "it" you are referring to here. > > I was trying to explain why starting in "bind" state is not a good idea for a > BMC in most of these cases where we want to be able to dynamically add a device. I think "it" is "something needs to be the moderator between the two operating systems". What is the external entity that handles the switching between the two? thanks, greg k-h
