Hi Bin, On Mon, 2019-03-11 at 23:28 +0800, Bin Meng wrote: > Hi Lukas, > > On Mon, Mar 11, 2019 at 2:03 AM Auer, Lukas > <lukas.a...@aisec.fraunhofer.de> wrote: > > Hi Bin, > > > > On Sun, 2019-03-10 at 22:57 +0800, Bin Meng wrote: > > > Hi Lukas, > > > > > > On Sun, Mar 10, 2019 at 9:44 PM Auer, Lukas > > > <lukas.a...@aisec.fraunhofer.de> wrote: > > > > Hi Bin, > > > > > > > > On Sun, 2019-03-10 at 09:07 +0800, Bin Meng wrote: > > > > > Hi Lukas, > > > > > > > > > > On Mon, Feb 11, 2019 at 6:13 AM Lukas Auer > > > > > <lukas.a...@aisec.fraunhofer.de> wrote: > > > > > > Re-add the previous compatible string "riscv-virtio-soc" to > > > > > > the > > > > > > soc > > > > > > device tree node to allow U-Boot and Linux to bind machine- > > > > > > specific > > > > > > drivers to it. The current compatible string "simple-bus" > > > > > > is > > > > > > retained. > > > > > > > > > > > > This is required by U-Boot to bind devices early, as part > > > > > > of > > > > > > the > > > > > > pre-relocation driver model. > > > > > > > > > > > > > > > > I see no problem with U-Boot working with current compatible > > > > > string > > > > > "simple-bus". In fact I had planned to remove the compatible > > > > > string > > > > > "riscv-virtio-soc" in U-Boot but did not get time to work on > > > > > it. > > > > > > > > > > > > > It is only required if U-Boot is running in machine-mode. For > > > > relocation it needs to use the CLINT driver to send appropriate > > > > IPIs to > > > > the other harts. To be able to probe the driver, the device and > > > > its > > > > parent device tree node (soc) must therefore be available in > > > > the > > > > pre- > > > > relocation device model. > > > > This patch was the easiest way I could think of for achieving > > > > this. > > > > It > > > > could be that there is a better way of solving this. > > > > > > > > > > I tested your SMP U-Boot series in both M-mode and S-mode, using > > > a 4 > > > core 'virt' target. Works fine. I am using QEMU 3.1.0 so it is > > > "simple-bus". > > > > > > > That is actually my fault, it should not work. > > What is happening is that U-Boot fails to relocate the secondary > > harts, > > because the CLINT driver cannot get the memory address of the CLINT > > device. This error is currently silently ignored. > > I still don't understand. Why does the CLINT driver fail to get the > memory address? U-Boot has been supporting "simpile-bus" for a long > time. It was because QEMU 3.0.0 generated the /soc node with > "riscv-virtio-soc" compatible string, U-Boot was taught to treat such > compatible string as a "simple-bus" too (that was the U-Boot commit > 27dc2c130e29)
That's correct. The problem with the default simple-bus U-Boot driver is that it does not have the DM_FLAG_PRE_RELOC flag set. The /soc and /soc/clint nodes are therefore not available before relocation, meaning that IPIs cannot be sent to relocate the secondary harts. Thanks, Lukas > > > The secondary harts are still waiting to receive IPIs, so booting > > Linux > > works fine, because U-Boot can now send IPIs. This will however > > break > > if U-Boot overwrites the code the secondary harts are running, > > which > > could happen when loading an image. > > > > I will update my SMP U-Boot series to print a warning if sending an > > IPI > > fails. > > > > Regards, > Bin
