> -----Original Message----- > From: Daniel P. Berrangé [mailto:berra...@redhat.com] > Sent: Friday, February 14, 2020 6:25 PM > To: miaoyubo <miaoy...@huawei.com> > Cc: peter.mayd...@linaro.org; shannon.zha...@gmail.com; > imamm...@redhat.com; qemu-devel@nongnu.org; Xiexiangyou > <xiexiang...@huawei.com>; m...@redhat.com > Subject: Re: [RFC 2/2] pci-expender-bus:Add pcie-root-port to pxb-pcie under > arm. > > On Fri, Feb 14, 2020 at 07:25:43AM +0000, miaoyubo wrote: > > > > > -----Original Message----- > > > From: Daniel P. Berrangé [mailto:berra...@redhat.com] > > > Sent: Thursday, February 13, 2020 9:52 PM > > > To: miaoyubo <miaoy...@huawei.com> > > > Cc: peter.mayd...@linaro.org; shannon.zha...@gmail.com; > > > imamm...@redhat.com; qemu-devel@nongnu.org; Xiexiangyou > > > <xiexiang...@huawei.com>; m...@redhat.com > > > Subject: Re: [RFC 2/2] pci-expender-bus:Add pcie-root-port to > > > pxb-pcie under arm. > > > > > > On Thu, Feb 13, 2020 at 03:49:52PM +0800, Yubo Miao wrote: > > > > From: miaoyubo <miaoy...@huawei.com> > > > > > > > > Since devices could not directly plugged into pxb-pcie, under arm, > > > > one pcie-root port is plugged into pxb-pcie. Due to the bus for > > > > each pxb-pcie is defined as 2 in acpi dsdt tables(one for > > > > pxb-pcie, one for pcie-root-port), only one device could be plugged into > one pxb-pcie. > > > > > > What is the cause of this arm specific requirement for pxb-pcie and > > > more importantly can be fix it so that we don't need this patch ? > > > I think it is highly undesirable to have such a per-arch difference > > > in configuration of the pxb-pcie device. It means any mgmt app which > > > already supports pxb-pcie will be broken and need to special case arm. > > > > > > > Thanks for your reply, Without this patch, the pxb-pcie is also > > useable, however, one extra pcie-root-port or pci-bridge or something > > else need to be defined by mgmt. app. This patch will could be abandoned. > > That's not really answering my question. IIUC, this pxb-pcie device works fine > on x86_64, and I want to know why it doesn't work on arm ? > Requiring different setups by the mgmt apps is not at all nice because it will > inevitably lead to broken arm setups. x86_64 gets far more testing & usage, > developers won't realize arm is different. > >
Thanks for replying. Currently, on x86_64, pxb-pcie devices is presented in acpi tables but on arm, It is not, only one main host bridge is presented for arm in acpi dsdt tables. That's why pxb-pcie works on x86_64 but doesn't work on arm. The patch 1/2 do the work to present and allocate resources for pxb-pcie in arm. For x86_64, if one device is going to be plugged into pxb-pcie, one extra pcie-root-port or pci-bridge have to be defined and plugged on pxb-pcie, then the device is plugged on the pcie-root-port or pci-bridge. This patch 2/2 just auto defined one pcie-root-port for arm. If this patch abandoned, the usage of pxb-pcie would be the same with x86_64, therefore, to keep the same step for x86 and arm, this patch 2/2 could be abandonded. > > Regards, > Daniel > -- > |: https://berrange.com -o- > https://www.flickr.com/photos/dberrange :| > |: https://libvirt.org -o- > https://fstop138.berrange.com :| > |: https://entangle-photo.org -o- > https://www.instagram.com/dberrange :| Regards, Miao
