On 15/04/2017 15:44, Haojian Zhuang wrote:
> If bit TPZ and bit TPRZ are set, the erase feature is implemented.
> If bit TPZ is set and bit TPRZ is clear, the discard feature is
> implemented. And discard is a non-secure variant of the erase
> functionality.
>
> So the detecting operation of EFI_ERASE_BLOCK_PROTOCOL, we should
> consider to support both functionality. Since discard functionality is
> only supported in some UFS devices.
>
> And both of these two features are relied on UNMAP command.
Hi,
you need to use WRITE SAME, with a zero payload and the UNMAP bit set in
the command descriptor, in order to achieve a "secure" erase
functionality. UNMAP is only an advisory command, and does not
guarantee that the blocks are unmapped.
Discard can use either WRITE SAME or UNMAP.
Also,
> // Bits TPE and TPRZ should both be set to enable the erase feature on
> UFS.
> + // Setting bit TPE and clearing bit TPRZ to enable the discard feature
> on UFS.
> //
> - if (((CapacityData16->LowestAlignLogic2 & BIT7) == 0) ||
> - ((CapacityData16->LowestAlignLogic2 & BIT6) == 0)) {
> + if ((CapacityData16->LowestAlignLogic2 & BIT7) == 0) {
> DEBUG ((
> EFI_D_VERBOSE,
> "ScsiDisk EraseBlock: Either TPE or TPRZ is not set: 0x%x.\n",
The debug message is now wrong.
Paolo
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