On Wed, Sep 26, 2012 at 12:59:47AM +0200, vj wrote: > Hello, > A this is my first contribution, so I'm basically requesting for comments. > > The attached patch adds support for Archos G9 tablet wich uses an OMAP4460 cpu. Nice :) I should have bought that one instead of a Acer. > > A question I have is what does omap_vector_init do? > It breaks usb-booting. I digged around a bit. The funny thing is that this was introduced with OMAP4 support and is only done on OMAP4. U-Boot instead has the following: > #if !defined(CONFIG_TEGRA2) > /* > * Setup vector: > * (OMAP4 spl TEXT_BASE is not 32 byte aligned. > * Continue to use ROM code vector only in OMAP4 spl) > */ > #if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD)) > /* Set V=0 in CP15 SCTRL register - for VBAR to point to vector > * */ > mrc p15, 0, r0, c1, c0, 0 @ Read CP15 SCTRL Register > bic r0, #CR_V @ V = 0 > mcr p15, 0, r0, c1, c0, 0 @ Write CP15 SCTRL Register > > /* Set vector address in CP15 VBAR register */ > ldr r0, =_start > mcr p15, 0, r0, c12, c0, 0 @Set VBAR > #endif > #endif /* !Tegra2 */ So in U-Boot it's done for every ARMv7 *except* OMAP4 (and Tegra) ARM has this information about it: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0434b/CIHHDAIH.html > Purpose > > Provides the exception base address for exceptions that are not > handled in monitor mode. > > Usage constraints > > The VBAR is: > > * only accessible in privileged modes > * only accessible in Secure state. I think this is necessary to move the exception vector from ROM to our own code. Does it work to read the VBAR register using the following instruction: MRC p15, 0, <Rd>, c12, c0, 0 ; Read VBAR Register Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
