Re: [edk2-devel] [PATCH V1 0/3] Customize lazy-accepted memory size for TDVF

["Min Xu" <min.m.xu@intel.com>]

On January 2, 2023 6:37 PM, Gerd Hoffmann wrote:
> On Mon, Dec 26, 2022 at 09:33:35AM +0800, Min Xu wrote:
> > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=4181
> >
> > Current lazy-accept accepts the memory under address of 4G. To improve
> > boot performance further more, we introduce the feature of customizing
> > the physical end address of lazy-accept in build time.
> 
> Do you have numbers?  I'm wondering how much of a difference this actually
> is, given that 2M pages is fast and tdx already uses all processors to accept
> memory ...
This feature is tested in Intel SPR platform (boot up a td guest configured with 4vCPU + 4G memory).
It costs about 91ms to accept memories under address of 0x20000000. As a comparison it costs about 240ms to accept memories under address of 0x100000000.

> 
> What happens in case the firmware runs out of memory in DXE phase?
We create an initrd which size is 881MB. The td guest is configured to accept memories under address of 0x20000000.
 1) Direct boot
If we set the boot mode as direct boot, then it will turn to next boot option. In our case it is a grub boot.
If the log message is turned on, then we can see below errors when trying to FetchBlob "initrd":
  AllocatePoolPages: failed to allocate 225423 pages
  AllocatePool: failed to allocate 923331624 bytes
  FetchBlob: failed to allocate 923331584 bytes for "initrd"
  Error: Image at 0001E152000 start failed: Out of Resources

2) Grub boot
If we set the boot mode as grub boot, then below error message is shown:
error: ../../grub-core/loader/i386/efi/linux.c:119:can't allocate initrd.
error: ../../grub-core/loader/i386/efi/linux.c:119:can't allocate initrd.
Press any key to continue...Press any key to continue...

After a while the boot process continued. Finally the td guest is successfully brought up.

Thanks
Min