{"id":2224336,"url":"http://patchwork.ozlabs.org/api/patches/2224336/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260417-sdcard-performance-b4-v4-5-119e66be10c2@avm.de/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260417-sdcard-performance-b4-v4-5-119e66be10c2@avm.de>","list_archive_url":null,"date":"2026-04-17T09:51:38","name":"[v4,5/7] hw/sd/sdcard: Add erase-blocks-as-zero option.","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"f17e977c1b594534ca20d90844f2c06c54de056a","submitter":{"id":91343,"url":"http://patchwork.ozlabs.org/api/people/91343/?format=json","name":"Christian Speich","email":"c.speich@avm.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260417-sdcard-performance-b4-v4-5-119e66be10c2@avm.de/mbox/","series":[{"id":500297,"url":"http://patchwork.ozlabs.org/api/series/500297/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=500297","date":"2026-04-17T09:51:34","name":"hw/sd: Improve performance of read/write/erase","version":4,"mbox":"http://patchwork.ozlabs.org/series/500297/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2224336/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2224336/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=avm.de header.i=@avm.de header.a=rsa-sha256\n header.s=mail header.b=Wm5S1lah;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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charset=\"utf-8\"","X-purgate-ID":"149429::1776419845-22F7A373-09464F27/0/0","X-purgate-type":"clean","X-purgate-size":"3423","X-purgate-Ad":"Categorized by eleven eXpurgate (R) https://www.eleven.de","X-purgate":["This mail is considered clean (visit https://www.eleven.de for\n further information)","clean"],"Received-SPF":"pass client-ip=212.42.244.119; envelope-from=c.speich@avm.de;\n helo=mail.avm.de","X-Spam_score_int":"-48","X-Spam_score":"-4.9","X-Spam_bar":"----","X-Spam_report":"(-4.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.54,\n DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001,\n RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Currently, erased blocks are filled with 0xFF. However SCR Bit 55\n(DATA_STAT_AFTER_ERASE) indicates that an erase produces zeros. One of\nthem is wrong.\n\nThis patch does two things.\n\nFirst it fixes the reporting of DATA_STAT_AFTER_ERASE in SCR to\ncorrectly reflect the content of erased blocks. We also increase the\nProduct Revision (REV in CID) to indicate to the guest that\nDATA_STAT_AFTER_ERASE is now reliable.\n\nSecondly, we introduce a erase-blocks-as-zero option, which allows the\nuser to choose if erased blocks should contain 0xFF or 0x00. The default\nis still 0xFF to remain compatible with current users.\n\nSigned-off-by: Christian Speich \n---\n hw/core/machine.c | 5 +++++\n hw/sd/sd.c | 15 +++++++++++++--\n 2 files changed, 18 insertions(+), 2 deletions(-)","diff":"diff --git a/hw/core/machine.c b/hw/core/machine.c\nindex 0aa77a57e956693208d77fea6af5853ed4904234..54e4c05c96e3cf35ab2e702ee81fba36457cadd7 100644\n--- a/hw/core/machine.c\n+++ b/hw/core/machine.c\n@@ -38,6 +38,11 @@\n #include \"hw/acpi/generic_event_device.h\"\n #include \"qemu/audio.h\"\n \n+GlobalProperty hw_compat_11_0[] = {\n+ { \"sdmmc-common\", \"erase-blocks-as-zero\", \"false\" },\n+};\n+const size_t hw_compat_11_0_len = G_N_ELEMENTS(hw_compat_11_0);\n+\n GlobalProperty hw_compat_10_2[] = {\n { \"scsi-block\", \"migrate-pr\", \"off\" },\n { \"isa-cirrus-vga\", \"global-vmstate\", \"true\" },\ndiff --git a/hw/sd/sd.c b/hw/sd/sd.c\nindex b27fed2e563e5971dd32787498eb8abed9ffe9be..0f997ed8cc80e38645101cb8f47c86f1c30d5a25 100644\n--- a/hw/sd/sd.c\n+++ b/hw/sd/sd.c\n@@ -162,6 +162,7 @@ struct SDState {\n /* Static properties */\n \n uint8_t spec_version;\n+ bool erase_blocks_as_zero;\n uint64_t boot_part_size;\n uint64_t rpmb_part_size;\n BlockBackend *blk;\n@@ -439,6 +440,9 @@ static void sd_set_scr(SDState *sd)\n sd->scr[0] |= 2; /* Spec Version 2.00 or Version 3.0X */\n sd->scr[1] = (2 << 4) /* SDSC Card (Security Version 1.01) */\n | 0b0101; /* 1-bit or 4-bit width bus modes */\n+ if (!sd->erase_blocks_as_zero) {\n+ sd->scr[1] |= (1 << 7); /* DATA_STAT_AFTER_ERASE: Erase produces 0xFF */\n+ }\n sd->scr[2] = 0x00; /* Extended Security is not supported. */\n if (sd->spec_version >= SD_PHY_SPECv3_01_VERS) {\n sd->scr[2] |= 1 << 7; /* Spec Version 3.0X */\n@@ -456,7 +460,7 @@ static void sd_set_scr(SDState *sd)\n #define MID 0xaa\n #define OID \"XY\"\n #define PNM \"QEMU!\"\n-#define PRV 0x01\n+#define PRV 0x02\n #define MDT_YR 2006\n #define MDT_MON 2\n \n@@ -1363,7 +1367,12 @@ static void sd_erase(SDState *sd)\n sd->erase_end = INVALID_ADDRESS;\n sd->csd[14] |= 0x40;\n \n- memset(sd->data, 0xff, erase_len);\n+ if (sd->erase_blocks_as_zero) {\n+ memset(sd->data, 0x0, erase_len);\n+ } else {\n+ memset(sd->data, 0xFF, erase_len);\n+ }\n+\n for (erase_addr = erase_start; erase_addr <= erase_end;\n erase_addr += erase_len) {\n if (sdsc) {\n@@ -3287,6 +3296,8 @@ static void emmc_realize(DeviceState *dev, Error **errp)\n \n static const Property sdmmc_common_properties[] = {\n DEFINE_PROP_DRIVE(\"drive\", SDState, blk),\n+ DEFINE_PROP_BOOL(\"erase-blocks-as-zero\", SDState, erase_blocks_as_zero,\n+ true),\n };\n \n static const Property sd_properties[] = {\n","prefixes":["v4","5/7"]}