Re: [dpdk-dev] [PATCH v5] eal: map uio resources after hugepages when the base_virtaddr is configured.

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

The explanation of the patch should be generic and impartial, i.e. when this and this happens, it results in such and such problem, and this patch fixes it by doing this and that. In other words, this will appear in the git history, so whoever is reading the commit log will be able to figure out what this patch does and why it's been applied.

Thomas, do we need to do similar changes to VFIO code, to keep consistency? Also, do we really need for this to depend on --base-virtaddr? Why not do it unconditionally, i.e. map PCI resources right after hugepages in memory?

Thanks,
Anatoly

-----Original Message-----
From: lxu [mailto:liang.xu@cinfotech.cn] 
Sent: Thursday, November 6, 2014 3:32 PM
To: dev@dpdk.org
Cc: Burakov, Anatoly; thomas.monjalon@6wind.com; De Lara Guarch, Pablo
Subject: [PATCH v5] eal: map uio resources after hugepages when the base_virtaddr is configured.

Sorry, I'm learning the right way to send a patch by git. 
I have a multiple processes application. When start the secondary process, I got error message "EAL: pci_map_resource(): cannot mmap(11, 0x7ffff7fba000, 0x20000, 0x0): Bad file descriptor (0x7ffff7fb9000)".
The secondary process links a lot of additional shared libraries, so the address 0x7ffff7fba000 had already be used.
I had fixed similar hugepages mmap problems by base_virtaddr. So I believe the uio resource should be mapped into base_virtaddr at this situation.
This patch try to fix it.


Signed-off-by: lxu <liang.xu@cinfotech.cn>
---
 lib/librte_eal/linuxapp/eal/eal_pci_uio.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_uio.c b/lib/librte_eal/linuxapp/eal/eal_pci_uio.c
index 7e62266..a2c9ab6 100644
--- a/lib/librte_eal/linuxapp/eal/eal_pci_uio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_uio.c
@@ -273,6 +273,24 @@ pci_get_uio_dev(struct rte_pci_device *dev, char *dstbuf,
 	return uio_num;
 }
 
+static inline const struct rte_memseg *
+get_physmem_last(void)
+{
+	const struct rte_memseg * seg = rte_eal_get_physmem_layout();
+	const struct rte_memseg * last = seg;
+	unsigned i = 0;
+
+	for (i=0; i<RTE_MAX_MEMSEG; i++, seg++) {
+		if (seg->addr == NULL)
+			break;
+
+		if(seg->addr > last->addr)
+		 	last = seg;
+
+	}
+	return last;
+}
+
 /* map the PCI resource of a PCI device in virtual memory */  int  pci_uio_map_resource(struct rte_pci_device *dev) @@ -290,6 +308,13 @@ pci_uio_map_resource(struct rte_pci_device *dev)
 	struct mapped_pci_resource *uio_res;
 	struct pci_map *maps;
 
+	/* map uio resource into user required virtual address */
+	static void * requested_addr;
+	if (internal_config.base_virtaddr && NULL == requested_addr) {
+		const struct rte_memseg * last = get_physmem_last();
+		requested_addr = RTE_PTR_ADD(last->addr, last->len);
+	}
+
 	dev->intr_handle.fd = -1;
 	dev->intr_handle.type = RTE_INTR_HANDLE_UNKNOWN;
 
@@ -371,10 +396,12 @@ pci_uio_map_resource(struct rte_pci_device *dev)
 			if (maps[j].addr != NULL)
 				fail = 1;
 			else {
-				mapaddr = pci_map_resource(NULL, fd, (off_t)offset,
+				mapaddr = pci_map_resource(requested_addr, fd, (off_t)offset,
 						(size_t)maps[j].size);
 				if (mapaddr == NULL)
 					fail = 1;
+				else if (NULL != requested_addr)
+					requested_addr = RTE_PTR_ADD(mapaddr, maps[j].size);
 			}
 
 			if (fail) {
--
1.9.1