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Re: [Xen-devel] [PATCH v3 2/8] hvmloader: Make the printfs more informative



On 21/06/13 10:35, George Dunlap wrote:
On 20/06/13 18:12, Stefano Stabellini wrote:
On Thu, 20 Jun 2013, George Dunlap wrote:
* Warn that you're relocating some BARs to 64-bit

* Warn that you're relocating guest pages, and how many

* Include upper 32-bits of the base register when printing the bar
   placement info

Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
CC: Ian Jackson <ian.jackson@xxxxxxxxxx>
CC: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
CC: Hanweidong <hanweidong@xxxxxxxxxx>
CC: Keir Fraser <keir@xxxxxxx>
---
  tools/firmware/hvmloader/pci.c |   13 ++++++++++---
  1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
index aa54bc1..d8592b0 100644
--- a/tools/firmware/hvmloader/pci.c
+++ b/tools/firmware/hvmloader/pci.c
@@ -213,10 +213,17 @@ void pci_setup(void)
              ((pci_mem_start << 1) != 0) )
          pci_mem_start <<= 1;
  -    if ( (pci_mem_start << 1) != 0 )
+    if ( (pci_mem_start << 1) != 0 ) {
+        printf("Low MMIO hole not large enough for all devices,"
+               " relocating some BARs to 64-bit\n");
          bar64_relocate = 1;
+    }
/* Relocate RAM that overlaps PCI space (in 64k-page chunks). */
+    if ( (pci_mem_start >> PAGE_SHIFT) < hvm_info->low_mem_pgend )
+ printf("Relocating 0x%lx pages to highmem for lowmem MMIO hole\n", + hvm_info->low_mem_pgend - (pci_mem_start >> PAGE_SHIFT));
Shouldn't this be:

min_t(unsigned int,
       hvm_info->low_mem_pgend - (pci_mem_start >> PAGE_SHIFT),
       (1u << 16) - 1);

to match exactly what we do in the relocation code?

No; the relocation is done in a loop which will run until the condition in the if above is satisfied.

We could, I suppose, do the printf on each iteration of the loop; if I'm doing the math right*, the maximum iterations around the loop should be 8, and a typical number would be just 1 or 2.

* Maximum MMIO size: 2GiB == 1<<31. In 4-k pages, that's 1<<(31-12) == 1<<19. This will do a batch of 1<<16 pages at a time, leaving 1<<3 iterations maximum, or 8. (1<<16 pages is 1<<(16+12) or 1<<28 bytes, or 1<<8 == 256 megabytes moved at a time.)


Regarding the message, what about:

printf("Relocating 0x%lx pages from 0x%lx to 0x%lx%lx to make room for a larger MMIO hole\n",
        min_t(unsigned int,
              hvm_info->low_mem_pgend - (pci_mem_start >> PAGE_SHIFT),
              (1u << 16) - 1),
         hvm_info->low_mem_pgend,
         hvm_info->high_mem_pgend);

Lemme see how it looks...

If you have a 2GiB MMIO hole, it looks like this:

(XEN) HVM42: Relocating 0xffff pages from 0e0001000 to 20f800000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 0d0002000 to 21f7ff000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 0c0003000 to 22f7fe000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 0b0004000 to 23f7fd000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 0a0005000 to 24f7fc000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 090006000 to 25f7fb000 for lowmem MMIO hole (XEN) HVM42: Relocating 0xffff pages from 080007000 to 26f7fa000 for lowmem MMIO hole (XEN) HVM42: Relocating 0x7 pages from 080000000 to 27f7f9000 for lowmem MMIO hole


Kind of ugly; I think I liked it better with just one printf.

 -George


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