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    SubjectRe: [PATCH v4 1/6] tpm: dynamically allocate active_banks array
    On Thu, Nov 08, 2018 at 07:20:51PM +0530, Nayna Jain wrote:
    > Based on a discussion with Ken, the count in the TPML_PCR_SELECTION returns
    > the number of possible algorithms supported. In the example below, two
    > possible algorithms - SHA1 and SHA256 - are returned.
    >
    > # /usr/local/bin/tssgetcapability -cap 5
    > 2 PCR selections
    >     hash TPM_ALG_SHA1
    >     TPMS_PCR_SELECTION length 3
    >     ff ff ff
    >     hash TPM_ALG_SHA256
    >     TPMS_PCR_SELECTION length 3
    >     00 00 00
    >
    > The pcr_select fields - "ff ff ff" and "00 00 00" - are bit masks for the
    > enabled PCRs. The SHA1 bank is enabled for all PCRs (0-23), while the SHA256
    > bank is not enabled.
    >
    > The current code works, but it unnecessarily extends some banks. Instead of
    > basing the number of active banks on the number of algorithms returned, it
    > should be based on the pcr_select field.
    >
    >    - Mimi & Nayna

    I would just allocate array of the size of possible banks and grow
    nr_active_banks for active algorithms to keep the code simple because
    we are talking about insignificant amount of wasted space (might be
    even zero bytes given how kernel allocators works)>

    /Jarkko

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