[tpm2] Re: tpm2_flushcontext stuck
Kenneth Goldman <kgoldman at us.ibm.com>
| Newsgroups | dev.linux.lists.tpm2 |
|---|---|
| Message-ID | <BN8PR15MB275326320CD1F689C1EDC804F27B9@BN8PR15MB2753.namprd15.prod.outlook.com> |
They way I use it: /dev/tpm0 is locking, one user at a time. I use it for debug only. IMHO, production applications should not use it. /dev/tpmrm0 is the multi-user interface. Use it for production applications, where the TPM is shared. I suspect (not sure) that /dev/tpm0 will have unexpected effects when the kernel is also trying to use the TPM. And as a newbie, I felt that the fact TPM exposes two devices (/dev/tpm0 and /dev/tpmrm0) under Linux is confusing and is making things more complicated. The architecture diagram (https://github.com/tpm2-software/tpm2-tss<https://github.com/tpm2-software/tpm2-tss>) shows all calls go through the Resource Manager but that is not the case in reality. I was wondering what is the benefit to have 2 devices instead of just one device in linux?
attachment.htm
(text/html, 2.9 KB)
<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
span.EmailStyle34
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal">They way I use it:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/dev/tpm0 is locking, one user at a time. I use it for debug only. IMHO, production applications should not use it.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/dev/tpmrm0 is the multi-user interface. Use it for production applications, where the TPM is shared.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I suspect (not sure) that /dev/tpm0 will have unexpected effects when the kernel is also trying to use the TPM.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt">
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">And as a newbie, I felt that the fact TPM exposes two devices (/dev/tpm0 and /dev/tpmrm0) under Linux is confusing and is making things more complicated. The architecture diagram (<a href="https://github.com/tpm2-software/tpm2-tss">https://github.com/tpm2-software/tpm2-tss</a>)
shows all calls go through the Resource Manager but that is not the case in reality. I was wondering what is the benefit to have 2 devices instead of just one device in linux? <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
</div>
</div>
</body>
</html>