From mboxrd@z Thu Jan 1 00:00:00 1970 From: Songmao Tian Date: Fri, 6 Jul 2007 19:53:38 +0800 Subject: [U-Boot-Users] =?GB2312?B?u9i4tDogW1UtQm9vdC1Vc2Vyc10gVS1Cb290LU5HID8=?= In-Reply-To: <20070703072229.C64DD353AF8@atlas.denx.de> References: <20070703000910.GA15081@pengutronix.de> <20070703072229.C64DD353AF8@atlas.denx.de> Message-ID: <7d73e7d80707060453v785b0003hab187444ce94de1b@mail.gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de what's the trick to use d-cache as memory? 2007/7/3, Wolfgang Denk : > In message <20070703000910.GA15081@pengutronix.de> you wrote: > > > > > You don't? How do you uncompress an image then? > > > > On Arm by default zImages are used to generate the uImage, so the kernel > > decompresses itself. > > For the Linux kernel, maybe. But there are many more things than just > Linux. Think for example about FPGA images, etc. > > > > Do you mean you don't relocate the code any more? > > > > It still gets copied from the address U-Boot starts (Flash) to RAM, but > > pointer offsets are not recalculated. This means that you must not use > > statically initialized pointers during startup since the code is not > > running at its link address. > > Are you doing this for all architectures now? > > > The Arm part has done this for years. On PowerPC we have the luxury of > > Yes, and this is my major critique to the ARM (and the MIPS, and > maybe other) ports. We should fix this. Like on PowerPC, U-Boot > should always be copied to the upper end of RAM instead of a > precalculated address, as this cannot cope with different RAM sizes. > > > having SRAM, so we can setup a stack and do SDRAM initialization in C > > before jumping to RAM. > > Not all PowerPC processors have on-chip or other static RAM; in some > cases we use (for example) the data cache as memory. Similar > techniqes should be possible on all architectures. > > Best regards, > > Wolfgang Denk > > -- > DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de > If God had a beard, he'd be a UNIX programmer. > > ------------------------------------------------------------------------- > This SF.net email is sponsored by DB2 Express > Download DB2 Express C - the FREE version of DB2 express and take > control of your XML. No limits. Just data. Click to get it now. > http://sourceforge.net/powerbar/db2/ > _______________________________________________ > U-Boot-Users mailing list > U-Boot-Users at lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/u-boot-users >