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The Root Port (identified by [1c36:0031]) doesn't support MSI-X. On some platforms it is configured to not advertise the capability at all, while on others it (mistakenly) does. This causes a panic during initialization by the pcieport driver, since it tries to configure the MSI-X capability. Specifically, when trying to access the MSI-X table a "non-existing addr" exception occurs. Example stacktrace snippet: SError Interrupt on CPU2, code 0xbf000000 -- SError CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.2.0-rc1-Jonny-14847-ge76f1d4a1828-dirty #33 Hardware name: Annapurna Labs Alpine V3 EVP (DT) pstate: 80000005 (Nzcv daif -PAN -UAO) pc : __pci_enable_msix_range+0x4e4/0x608 lr : __pci_enable_msix_range+0x498/0x608 sp : ffffff80117db700 x29: ffffff80117db700 x28: 0000000000000001 x27: 0000000000000001 x26: 0000000000000000 x25: ffffffd3e9d8c0b0 x24: 0000000000000000 x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000001 x20: 0000000000000000 x19: ffffffd3e9d8c000 x18: ffffffffffffffff x17: 0000000000000000 x16: 0000000000000000 x15: ffffff80116496c8 x14: ffffffd3e9844503 x13: ffffffd3e9844502 x12: 0000000000000038 x11: ffffffffffffff00 x10: 0000000000000040 x9 : ffffff801165e270 x8 : ffffff801165e268 x7 : 0000000000000002 x6 : 00000000000000b2 x5 : ffffffd3e9d8c2c0 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffffd3e9844680 Kernel panic - not syncing: Asynchronous SError Interrupt CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.2.0-rc1-Jonny-14847-ge76f1d4a1828-dirty #33 Hardware name: Annapurna Labs Alpine V3 EVP (DT) Call trace: dump_backtrace+0x0/0x140 show_stack+0x14/0x20 dump_stack+0xa8/0xcc panic+0x140/0x334 nmi_panic+0x6c/0x70 arm64_serror_panic+0x74/0x88 __pte_error+0x0/0x28 el1_error+0x84/0xf8 __pci_enable_msix_range+0x4e4/0x608 pci_alloc_irq_vectors_affinity+0xdc/0x150 pcie_port_device_register+0x2b8/0x4e0 pcie_portdrv_probe+0x34/0xf0 Notice that this quirk also disables MSI (which may work, but hasn't been tested nor has a current use case), since currently there is no standard way to disable only MSI-X. Signed-off-by: Jonathan Chocron <jonnyc@amazon.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reviewed-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com> Reviewed-by: Andrew Murray <andrew.murray@arm.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.