FWIW, we saw similar problems with a 3rd party SAS driver as well. It
provided only the BLOCK_IO protocol, and would error out if asked to
perform a read of 0x8000 or more blocks (16MB.) That broke a particular
version of Microsoft's boot loader, and there was nothing we could do
about it in our BIOS.
So it sounds like this sort of problem is widespread.
Brian Johnson
On 11/19/2013 03:10 AM, Mike Maslenkin wrote:
> And we saw similar problems too.
>
> In our case the problem was in large PIO transfers.
> Since edk2 code base uses PIO for ATAPI devices, we are unable to handle
> such reads in our VM, because we have a 1MB bounce buffer for PIO.
>
> There were two solutions implemented:
> 1. We have added DMA support.
> 2. We have limited maximum transfer size for all block devices to 1 MB
> (in ScsiDiskDxe).
> //
> // limit the data bytes that can be transferred by one Read(10) or
> Read(16) Command
> //
> if (!ScsiDiskDevice->Cdb16Byte) {
> - MaxBlock = 0xFFFF;
> + MaxBlock = 0x200; // 1mb
> } else {
> MaxBlock = 0xFFFFFFFF;
> }
>
> The second solution is not so good, and I started to think about
> splitting request at
> AtaAtapiPassThruDxe, before submitting it to ATA device.
>
> Hope it helps.
>
> On Mon, 2013-11-18 at 19:35 -0800, H. Peter Anvin wrote:
>> On 11/18/2013 05:47 PM, David F. wrote:
>>> Thanks - I found the grub option for set debug= (I couldn't use all
>>> since it would lock up - but used disk,efidisk,modules,loader) and can
>>> see it reads 0x100 sectors from sector 0x500 then reads 0x4C00 sectors
>>> from sector 0x600. So perhaps that's it. Yes, legacy reads in the
>>> same inirmfs.gz file (which occupies 0x5AF to 0x525C) but I'm sure it
>>> does it in smaller chunks.
>>
>> We saw similar problems with extremely large reads while developing the
>> Linux EFI boot stub. We ended up capping the size of any one read call
>> to 1 MB. Sad but true.
>>
>> -hpa
>>
------------------------------------------------------------------------------
Shape the Mobile Experience: Free Subscription
Software experts and developers: Be at the forefront of tech innovation.
Intel(R) Software Adrenaline delivers strategic insight and game-changing
conversations that shape the rapidly evolving mobile landscape. Sign up now.
http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/edk2-devel
