From 5b11abfdb572bf9284e596dd198ac2aaf95b6616 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Sun, 8 Feb 2009 14:27:21 +0000 Subject: [PATCH] powerpc/pci: mmap anonymous memory when legacy_mem doesn't exist The new legacy_mem file in sysfs is causing problems with X on machines that don't support legacy memory access. The way I initially implemented it, we would fail with -ENXIO when trying to mmap it, thus exposing to X that we do support the API but there is no legacy memory. Unfortunately, X poor error handling is causing it to fail to start when it gets this error. This implements a workaround hack that instead maps anonymous memory instead (using shmem if VM_SHARED is set, just like /dev/zero does). Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/pci-common.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c index 19b12d2cbb4b..0f4181272311 100644 --- a/arch/powerpc/kernel/pci-common.c +++ b/arch/powerpc/kernel/pci-common.c @@ -561,8 +561,21 @@ int pci_mmap_legacy_page_range(struct pci_bus *bus, (unsigned long long)(offset + size - 1)); if (mmap_state == pci_mmap_mem) { - if ((offset + size) > hose->isa_mem_size) - return -ENXIO; + /* Hack alert ! + * + * Because X is lame and can fail starting if it gets an error trying + * to mmap legacy_mem (instead of just moving on without legacy memory + * access) we fake it here by giving it anonymous memory, effectively + * behaving just like /dev/zero + */ + if ((offset + size) > hose->isa_mem_size) { + printk(KERN_DEBUG + "Process %s (pid:%d) mapped non-existing PCI legacy memory for 0%04x:%02x\n", + current->comm, current->pid, pci_domain_nr(bus), bus->number); + if (vma->vm_flags & VM_SHARED) + return shmem_zero_setup(vma); + return 0; + } offset += hose->isa_mem_phys; } else { unsigned long io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;