On 28/08/2012 22:50, Jonathan Tripathy wrote:
On 28/08/2012 22:41, Keir Fraser wrote:
On 28/08/2012 22:13, "Jonathan Tripathy" <jonnyt@xxxxxxxxxxx> wrote:
Keir Fraser wrote:
On 28/08/2012 20:36, "Jonathan Tripathy" <jonnyt@xxxxxxxxxxx> wrote:
Thanks for the clarification.
So from a security/reliability standpoint, nothing will be
affected by
flipping the if block?
It should simply make it more likely that Xen sees all your RAM. ;)
-- Keir
Hi Everyone,
I reversed the if block in setup.c and now my server can see the
full
32GB of RAM. I haven't submitted a patch yet as we have run into
another
(possibly unrelated to xen) issue with this server build that we are
working on. Once we complete our full testing, a patch will be
submitted :)
In this case, I will re-make the patch myself and check it in.
Since it is a
trivial one.
Thanks,
Keir
Thanks Keir
Now done. xen-unstable:25786
-- Keir
Hi Keir,
Thanks for doing that. However, the ordering of the if block in my
code that I used was slightly different from your commit. Perhaps
this doesn't make too much of a difference?
Thanks
Ooops, typo'd the code (I had to recreate the changes as I deleted my
source tree). Here is the version I used:
if ( mbi->flags & MBI_MEMMAP )
{
memmap_type = "Multiboot-e820";
while ( (bytes < mbi->mmap_length) && (e820_raw_nr < E820MAX) )
{
memory_map_t *map = __va(mbi->mmap_addr + bytes);
/*
* This is a gross workaround for a BIOS bug. Some
bootloaders do
* not write e820 map entries into pre-zeroed memory. This is
* okay if the BIOS fills in all fields of the map entry, but
* some broken BIOSes do not bother to write the high word of
* the length field if the length is smaller than 4GB. We
* detect and fix this by flagging sections below 4GB that
* appear to be larger than 4GB in size.
*/
if ( (map->base_addr_high == 0) && (map->length_high != 0) )
{
if ( !e820_warn )
{
printk("WARNING: Buggy e820 map detected and fixed "
"(truncated length fields).\n");
e820_warn = 1;
}
map->length_high = 0;
}
e820_raw[e820_raw_nr].addr =
((u64)map->base_addr_high << 32) |
(u64)map->base_addr_low;
e820_raw[e820_raw_nr].size =
((u64)map->length_high << 32) | (u64)map->length_low;
e820_raw[e820_raw_nr].type = map->type;
e820_raw_nr++;
bytes += map->size + 4;
}
}
else if ( mbi->flags & MBI_MEMLIMITS )
{
memmap_type = "Multiboot-e801";
e820_raw[0].addr = 0;
e820_raw[0].size = mbi->mem_lower << 10;
e820_raw[0].type = E820_RAM;
e820_raw[1].addr = 0x100000;
e820_raw[1].size = mbi->mem_upper << 10;
e820_raw[1].type = E820_RAM;
e820_raw_nr = 2;
}
else if ( e820_raw_nr != 0 )
{
memmap_type = "Xen-e820";
}
else if ( bootsym(lowmem_kb) )
{
memmap_type = "Xen-e801";
e820_raw[0].addr = 0;
e820_raw[0].size = bootsym(lowmem_kb) << 10;
e820_raw[0].type = E820_RAM;
e820_raw[1].addr = 0x100000;
e820_raw[1].size = bootsym(highmem_kb) << 10;
e820_raw[1].type = E820_RAM;
e820_raw_nr = 2;
}
else
{
EARLY_FAIL("Bootloader provided no memory information.\n");
}
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