On 29.06.2012 22:49, stuart_ha...@dell.com wrote: >>>>> Vladimir, >>>>> >>>>> The 2.00rc1 version of grub2 still doesn't fix the efi memory map >>>> buffer size I've been working on (though I can see you are now >>>> allocating the efi memory map buffer very shortly before you are >>>> calling grub_efi_finish_boot_services()). >>>>> >>>>> Increasing the mmap_size in find_efi_mmap_size()--as in the patch >>>> immediately above this text--does fix the problem. Even adding (2 >> << >>>> 12) (instead of (1 << 12)) to the mmap_size will work on the system >>> I'm >>>> testing with. >>>>> >>>> >>>> I've changed it to 3. Thanks. It's annoying that even such simple >>>> operations as we have between find_efi_mmap and finish drastically >>>> increase memory map size. >>>> >>>> -- >>>> Regards >>>> Vladimir 'φ-coder/phcoder' Serbinenko >>> >>> Thanks! I completely agree that it is annoying. >>> >> >> FYI, while grub-2.00 works on my system now, someone else here at Dell >> has tested it and found that it still doesn't work. (I verified that >> they were indeed using version 2.00, and saw the error myself). >> >> I have no idea how or why the memory map size is growing that much. As >> I get time, I'll try to figure that out... > > FYI again: > > I've found the problem. The memory map is not growing wildly... it is more > of a firmware "quirk." The firmware is thinking it needs a larger buffer > than it actually needs. So calls to GetMemoryMap with a buffer that is > smaller than (say) 52368 bytes will return EFI_BUFFER_TOO_SMALL and say that > the buffer needs to be 52368 bytes, but then when you call it with a buffer > that's 52368 bytes, it will put the memory map into the buffer and tell you > that the memory map is in fact only (say) 24576 bytes. > > Unfortunately, right now, find_efi_mmap_size() will then return 24576 bytes > (plus 3 pages, aligned to a page size), which isn't enough, but not because > the memory map size is growing... > > I'll send in a patch for grub that will make it immune to this quirk... it > should be pretty low risk (I'm thinking modify find_efi_mmap_size() to use > the value of mmap_size that was passed to grub_efi_get_memory_map(), rather > than the value of mmap_size that was returned from that function.) With > that, I don't believe it would even need to add 3 pages to the memory map > size (I watched the memory map size, and it is not growing significantly). >
What about this:
=== modified file 'grub-core/loader/i386/linux.c'
--- grub-core/loader/i386/linux.c 2012-06-27 20:55:09 +0000
+++ grub-core/loader/i386/linux.c 2012-06-29 21:12:53 +0000
@@ -118,12 +118,13 @@ find_efi_mmap_size (void)
int ret;
grub_efi_memory_descriptor_t *mmap;
grub_efi_uintn_t desc_size;
+ grub_efi_uintn_t cur_mmap_size = mmap_size;
- mmap = grub_malloc (mmap_size);
+ mmap = grub_malloc (cur_mmap_size);
if (! mmap)
return 0;
- ret = grub_efi_get_memory_map (&mmap_size, mmap, 0, &desc_size, 0);
+ ret = grub_efi_get_memory_map (&cur_mmap_size, mmap, 0, &desc_size, 0);
grub_free (mmap);
if (ret < 0)
@@ -134,6 +135,8 @@ find_efi_mmap_size (void)
else if (ret > 0)
break;
+ if (mmap_size < cur_mmap_size)
+ mmap_size = cur_mmap_size;
mmap_size += (1 << 12);
}
It will take the largest size returned which should be safe.
--
Regards
Vladimir 'φ-coder/phcoder' Serbinenko
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