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| author | Mattias Nissler <mnissler@rivosinc.com> | 2024-09-10 14:35:12 -0700 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2024-11-04 09:22:58 -0500 |
| commit | c3ec57e495b032047ddfef2075792340c407532a (patch) | |
| tree | bf4160069918ba774792a8991102ac2c8fd85833 | |
| parent | 92ec7805190313c9e628f8fc4eb4f932c15247bd (diff) | |
| download | focaccia-qemu-c3ec57e495b032047ddfef2075792340c407532a.tar.gz focaccia-qemu-c3ec57e495b032047ddfef2075792340c407532a.zip | |
softmmu: Expand comments describing max_bounce_buffer_size
Clarify how the parameter gets configured and how it is used when servicing DMA mapping requests targeting indirect memory regions. Signed-off-by: Mattias Nissler <mnissler@rivosinc.com> Message-Id: <20240910213512.843130-1-mnissler@rivosinc.com> Acked-by: Peter Xu <peterx@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
| -rw-r--r-- | include/exec/memory.h | 9 | ||||
| -rw-r--r-- | include/hw/pci/pci_device.h | 6 |
2 files changed, 13 insertions, 2 deletions
diff --git a/include/exec/memory.h b/include/exec/memory.h index e5e865d1a9..9458e2801d 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -1104,7 +1104,14 @@ struct AddressSpace { QTAILQ_HEAD(, MemoryListener) listeners; QTAILQ_ENTRY(AddressSpace) address_spaces_link; - /* Maximum DMA bounce buffer size used for indirect memory map requests */ + /* + * Maximum DMA bounce buffer size used for indirect memory map requests. + * This limits the total size of bounce buffer allocations made for + * DMA requests to indirect memory regions within this AddressSpace. DMA + * requests that exceed the limit (e.g. due to overly large requested size + * or concurrent DMA requests having claimed too much buffer space) will be + * rejected and left to the caller to handle. + */ size_t max_bounce_buffer_size; /* Total size of bounce buffers currently allocated, atomically accessed */ size_t bounce_buffer_size; diff --git a/include/hw/pci/pci_device.h b/include/hw/pci/pci_device.h index 91df40f989..8eaf0d58bb 100644 --- a/include/hw/pci/pci_device.h +++ b/include/hw/pci/pci_device.h @@ -168,7 +168,11 @@ struct PCIDevice { char *failover_pair_id; uint32_t acpi_index; - /* Maximum DMA bounce buffer size used for indirect memory map requests */ + /* + * Indirect DMA region bounce buffer size as configured for the device. This + * is a configuration parameter that is reflected into bus_master_as when + * realizing the device. + */ uint32_t max_bounce_buffer_size; }; |