From mboxrd@z Thu Jan 1 00:00:00 1970 From: Artem Alimarine Subject: Wierd code in Entry.S Date: Thu, 09 Jul 2009 15:11:19 +0200 Message-ID: <4A55EC77.4040402@stromasys.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="------------010104060302060209050802" To: linux-parisc@vger.kernel.org Return-path: List-ID: List-Id: linux-parisc.vger.kernel.org This is a multi-part message in MIME format. --------------010104060302060209050802 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Hi guys, I am new to PARISC and to this forum. I have a small question. There is an instruction in entry.S that I do not understand. It is in the the macro make_insert_tlb Kernel 2.6.26.2: 537 /* Enforce uncacheable pages. 538 * This should ONLY be use for MMIO on PA 2.0 machines. 539 * Memory/DMA is cache coherent on all PA2.0 machines we support 540 * (that means T-class is NOT supported) and the memory controllers 541 * on most of those machines only handles cache transactions. 542 */ 543 extrd,u,*= \pte,_PAGE_NO_CACHE_BIT+32,1,%r0 544 depi 1,12,1,\prot The DEPI instruction on a 64-bit machine sets bit 44=32+12, whereas we use the value as the argument to IDTLBT, which expects bit 12 to be used instead. Does it mean that the U-bit is never set and the authorization id gets corrupted??? Is it a bug or my misunderstanding of the code??? Best regards, Artem --------------010104060302060209050802 Content-Type: text/x-vcard; charset=utf-8; name="artem_alimarine.vcf" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="artem_alimarine.vcf" begin:vcard fn:dr. Artem Alimarine n:Alimarine;Artem org:STROMASYS SA adr:;;De Zaale 11;Eindhoven;;5612AJ;The Netherlands email;internet:artem.alimarine@stromasys.com title:Software Architect tel;work:+31-40-2390863 tel;fax:+31-40-2390800 x-mozilla-html:FALSE version:2.1 end:vcard --------------010104060302060209050802--